1.
B. Vink, Schot; Toxopeus, S. L.
A Verification and Validation Study of CFD Simulations for the Flow Around A Tug Conference
20th Numerical Towing Tank Symposium (NuTTS), Wageningen, The Netherlands, 2017.
@conference{Vink2017,
title = {A Verification and Validation Study of CFD Simulations for the Flow Around A Tug},
author = {Vink, B., Schot, J., Vaz, G. and Toxopeus, S.L.},
url = {http://www.marin.nl/web/Publications/Publication-items/A-Verification-and-Validation-Study-of-CFD-Simulations-for-the-Flow-Around-A-Tug.htm},
year = {2017},
date = {2017-10-03},
booktitle = {20th Numerical Towing Tank Symposium (NuTTS), Wageningen, The Netherlands},
abstract = {An important vessel for the operational process in a harbour is the tug, a vessel built for the specific purpose of quickly manoeuvring larger vessels in waterways. The key features of a tug are the towing and escorting performances under optimal conditions, which are often reached when sailing under drift at high Froude numbers. Potential users or buyers are comparing tugs on these key features. Thus, for tug designers it is of significant importance to correctly predict the performance of new designs, therewith enabling themselves to verify possible improvements. These predictions, based on lift and drag characteristics of the hull and appendages, are frequently performed using free running or captive model tests, which can be expensive, give no thorough insight in flow specifics and although large-scale models are used still suffer from scale effects. An alternative approach is the use of viscous flow computations, also called Computational Fluid Dynamics (CFD).
This present work will initially estimate the experimental uncertainties from captive model tests to obtain correct validation material. Thereafter a verification and validation exercise of free surface simulations with the KSKL turbulence model and a drift angle of 15 deg will be presented. These are followed by a turbulence sensitivity study of the KSKL, SST, EARSM and DDES turbulence model and finally simulations at other drift angles with the KSKL turbulence will be presented.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
An important vessel for the operational process in a harbour is the tug, a vessel built for the specific purpose of quickly manoeuvring larger vessels in waterways. The key features of a tug are the towing and escorting performances under optimal conditions, which are often reached when sailing under drift at high Froude numbers. Potential users or buyers are comparing tugs on these key features. Thus, for tug designers it is of significant importance to correctly predict the performance of new designs, therewith enabling themselves to verify possible improvements. These predictions, based on lift and drag characteristics of the hull and appendages, are frequently performed using free running or captive model tests, which can be expensive, give no thorough insight in flow specifics and although large-scale models are used still suffer from scale effects. An alternative approach is the use of viscous flow computations, also called Computational Fluid Dynamics (CFD).
This present work will initially estimate the experimental uncertainties from captive model tests to obtain correct validation material. Thereafter a verification and validation exercise of free surface simulations with the KSKL turbulence model and a drift angle of 15 deg will be presented. These are followed by a turbulence sensitivity study of the KSKL, SST, EARSM and DDES turbulence model and finally simulations at other drift angles with the KSKL turbulence will be presented.
This present work will initially estimate the experimental uncertainties from captive model tests to obtain correct validation material. Thereafter a verification and validation exercise of free surface simulations with the KSKL turbulence model and a drift angle of 15 deg will be presented. These are followed by a turbulence sensitivity study of the KSKL, SST, EARSM and DDES turbulence model and finally simulations at other drift angles with the KSKL turbulence will be presented.
2.
A. Maximiano, Vaz; Scharnke, J.
CFD Verification and Validation Study for a Captive Bullet Entry in Calm Water Conference
OMAE ASME 36th International Conference on Ocean, Offshore and Arctic Engineering, Trondheim, Norway, 2017.
@conference{Maximiano2017,
title = {CFD Verification and Validation Study for a Captive Bullet Entry in Calm Water},
author = {Maximiano, A., Vaz, G. and Scharnke, J.},
url = {http://www.marin.nl/web/Publications/Publication-items/CFD-Verification-and-Validation-Study-for-a-Captive-Bullet-Entry-in-Calm-Water.htm},
year = {2017},
date = {2017-06-25},
booktitle = {OMAE ASME 36th International Conference on Ocean, Offshore and Arctic Engineering, Trondheim, Norway},
pages = {OMAE2017-61666},
abstract = {As a step towards complex impact loads cases, e.g. lifeboat drop tests or ship/platform slamming in waves, a verification and validation (V&V) study is carried out with an open-usage community based CFD code ReFRESCO for a simple impact load test case: a captive axisymmetric generic lifeboat shape (bullet) that penetrates the water surface at a constant velocity and angle of attack. The quantities of interest are the body fixed longitudinal force FX, vertical force FZ, and pitch moment MYY.
The influence of the iterative convergence level, domain size and free surface modelling are investigated. Seven different grids and four time steps were used to assess the grid and time step sensitivity, in a total of 28 calculations. For the tested grids and time steps it was found that the results are more sensitive to the grid resolution than to the time step. The pressure distribution on the hull is correlated with the trends observed in the loads, and the relation between between relative and static pressure is found to be important for the calculated loads. An experimental test campaign was previously carried out by MARIN, and its results are used to validate the simulations performed. A very good match between experiments and simulations is found.
A V&V study is performed for the quantities of interest at nine different time instants covering the impact phase. The numerical uncertainties are obtained from a solution verification procedure [1]. The experimental uncertainties are estimated, and a validation exercise carried out according to the ASME standards [2]. The outcome of the validation exercise is an estimated 95% confidence interval for the modelling error, M. For FX the modelling error is below 15 N, for 8 out of 9 time instants. For FZ the modelling error is below 14 N, except at the time instants where, due to vibrations in the experimental setup, a larger value (up to 23 N) is found. For MYY the modelling error is under 5Nm. These results provide confidence in ReFRESCO for the simulation of free surface impact flows.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
As a step towards complex impact loads cases, e.g. lifeboat drop tests or ship/platform slamming in waves, a verification and validation (V&V) study is carried out with an open-usage community based CFD code ReFRESCO for a simple impact load test case: a captive axisymmetric generic lifeboat shape (bullet) that penetrates the water surface at a constant velocity and angle of attack. The quantities of interest are the body fixed longitudinal force FX, vertical force FZ, and pitch moment MYY.
The influence of the iterative convergence level, domain size and free surface modelling are investigated. Seven different grids and four time steps were used to assess the grid and time step sensitivity, in a total of 28 calculations. For the tested grids and time steps it was found that the results are more sensitive to the grid resolution than to the time step. The pressure distribution on the hull is correlated with the trends observed in the loads, and the relation between between relative and static pressure is found to be important for the calculated loads. An experimental test campaign was previously carried out by MARIN, and its results are used to validate the simulations performed. A very good match between experiments and simulations is found.
A V&V study is performed for the quantities of interest at nine different time instants covering the impact phase. The numerical uncertainties are obtained from a solution verification procedure [1]. The experimental uncertainties are estimated, and a validation exercise carried out according to the ASME standards [2]. The outcome of the validation exercise is an estimated 95% confidence interval for the modelling error, M. For FX the modelling error is below 15 N, for 8 out of 9 time instants. For FZ the modelling error is below 14 N, except at the time instants where, due to vibrations in the experimental setup, a larger value (up to 23 N) is found. For MYY the modelling error is under 5Nm. These results provide confidence in ReFRESCO for the simulation of free surface impact flows.
The influence of the iterative convergence level, domain size and free surface modelling are investigated. Seven different grids and four time steps were used to assess the grid and time step sensitivity, in a total of 28 calculations. For the tested grids and time steps it was found that the results are more sensitive to the grid resolution than to the time step. The pressure distribution on the hull is correlated with the trends observed in the loads, and the relation between between relative and static pressure is found to be important for the calculated loads. An experimental test campaign was previously carried out by MARIN, and its results are used to validate the simulations performed. A very good match between experiments and simulations is found.
A V&V study is performed for the quantities of interest at nine different time instants covering the impact phase. The numerical uncertainties are obtained from a solution verification procedure [1]. The experimental uncertainties are estimated, and a validation exercise carried out according to the ASME standards [2]. The outcome of the validation exercise is an estimated 95% confidence interval for the modelling error, M. For FX the modelling error is below 15 N, for 8 out of 9 time instants. For FZ the modelling error is below 14 N, except at the time instants where, due to vibrations in the experimental setup, a larger value (up to 23 N) is found. For MYY the modelling error is under 5Nm. These results provide confidence in ReFRESCO for the simulation of free surface impact flows.
3.
A.H. Koop, Cozijn; Vaz, G.
Determining Thruster-Hull Interaction for a Drill-Ship Using CFD Conference
OMAE ASME 36th International Conference on Ocean, Offshore and Arctic Engineering, Trondheim, Norway, 2017.
@conference{Koop2017,
title = {Determining Thruster-Hull Interaction for a Drill-Ship Using CFD},
author = {Koop, A.H., Cozijn, H.C., Schrijvers, P. and Vaz, G.},
url = {http://www.marin.nl/web/Publications/Publication-items/Determining-ThrusterHull-Interaction-for-a-DrillShip-Using-CFD.htm},
year = {2017},
date = {2017-06-01},
booktitle = {OMAE ASME 36th International Conference on Ocean, Offshore and Arctic Engineering, Trondheim, Norway},
pages = {OMAE2017-61485},
abstract = {In this paper CFD results are presented for the thruster-hull interaction effects for a drillship with 6 azimuthing thrusters. The results using different approaches to model or simulate the propeller are compared and their advantages and disadvantages are discussed. The approaches investigated are the so-called Frozen Rotor approach, where the propeller rotation is modeled, the Actuator Disk approach with prescribed body forces and the unsteady Sliding Interface approach where the motion of the propeller is simulated in time.
First, open-water calculations for a tilted thruster are carried out using the Frozen Rotor approach. The open-water calculations are repeated using the Actuator Disk prescribing the propeller thrust and torque distribution obtained from the Frozen Rotor calculations. The results with Actuator Disk are very similar for the unit thrust and nozzle thrust compared to the results using the Frozen Rotor approach. Furthermore, the results using the Frozen Rotor or the Actuator Disk are very close to the experimental results for the nozzle thrust.
The thruster-hull interaction of one active thruster under the drillship is investigated using the Actuator Disk approach, the Frozen Rotor Approach and the Sliding Interface approach. A comparison to experimental results is presented for the thruster-hull interaction coefficients. Using the Actuator Disk a good agreement with the experiments is obtained. The results using the Actuator Disk and Sliding Interface are very similar to each other, but the computational costs for the Sliding Interface method are at least a factor 20 higher. The results using the Frozen Rotor deviate due to an unphysical wake behind the thruster.
Based on the results presented in this paper we conclude that, using the steady-state approach with the Actuator Disk, CFD can be a cost-efficient and accurate method to determine the thruster-hull interaction effects at bollard pull conditions for a typical offshore vessel.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
In this paper CFD results are presented for the thruster-hull interaction effects for a drillship with 6 azimuthing thrusters. The results using different approaches to model or simulate the propeller are compared and their advantages and disadvantages are discussed. The approaches investigated are the so-called Frozen Rotor approach, where the propeller rotation is modeled, the Actuator Disk approach with prescribed body forces and the unsteady Sliding Interface approach where the motion of the propeller is simulated in time.
First, open-water calculations for a tilted thruster are carried out using the Frozen Rotor approach. The open-water calculations are repeated using the Actuator Disk prescribing the propeller thrust and torque distribution obtained from the Frozen Rotor calculations. The results with Actuator Disk are very similar for the unit thrust and nozzle thrust compared to the results using the Frozen Rotor approach. Furthermore, the results using the Frozen Rotor or the Actuator Disk are very close to the experimental results for the nozzle thrust.
The thruster-hull interaction of one active thruster under the drillship is investigated using the Actuator Disk approach, the Frozen Rotor Approach and the Sliding Interface approach. A comparison to experimental results is presented for the thruster-hull interaction coefficients. Using the Actuator Disk a good agreement with the experiments is obtained. The results using the Actuator Disk and Sliding Interface are very similar to each other, but the computational costs for the Sliding Interface method are at least a factor 20 higher. The results using the Frozen Rotor deviate due to an unphysical wake behind the thruster.
Based on the results presented in this paper we conclude that, using the steady-state approach with the Actuator Disk, CFD can be a cost-efficient and accurate method to determine the thruster-hull interaction effects at bollard pull conditions for a typical offshore vessel.
First, open-water calculations for a tilted thruster are carried out using the Frozen Rotor approach. The open-water calculations are repeated using the Actuator Disk prescribing the propeller thrust and torque distribution obtained from the Frozen Rotor calculations. The results with Actuator Disk are very similar for the unit thrust and nozzle thrust compared to the results using the Frozen Rotor approach. Furthermore, the results using the Frozen Rotor or the Actuator Disk are very close to the experimental results for the nozzle thrust.
The thruster-hull interaction of one active thruster under the drillship is investigated using the Actuator Disk approach, the Frozen Rotor Approach and the Sliding Interface approach. A comparison to experimental results is presented for the thruster-hull interaction coefficients. Using the Actuator Disk a good agreement with the experiments is obtained. The results using the Actuator Disk and Sliding Interface are very similar to each other, but the computational costs for the Sliding Interface method are at least a factor 20 higher. The results using the Frozen Rotor deviate due to an unphysical wake behind the thruster.
Based on the results presented in this paper we conclude that, using the steady-state approach with the Actuator Disk, CFD can be a cost-efficient and accurate method to determine the thruster-hull interaction effects at bollard pull conditions for a typical offshore vessel.
4.
A.R. Starke, Drakopoulos; Turnock, S. R.
VII International Conference on Computational Methods in Marine Engineering (MARINE2017), 2017.
@conference{Starke2017,
title = {RANS-based full-scale power predictions for a general cargo vessel, and comparison with sea-trial results},
author = {Starke, A.R., Drakopoulos, K., Toxopeus, S.L. and Turnock, S.R.},
url = {http://www.marin.nl/web/Publications/Publication-items/RANSbased-fullscale-power-predictions-for-a-general-cargo-vessel-and-comparison-with-seatrial-results.htm},
year = {2017},
date = {2017-05-01},
booktitle = {VII International Conference on Computational Methods in Marine Engineering (MARINE2017)},
abstract = {Blind self-propulsion predictions for the 2016 LR Workshop on Ship Scale Hydrodynamic Computer Simulation have been carried out to simulate the full scale performance of a self-propelled ship in ballast. The single screw ship of 11542 tonnes had been scanned in drydock so the computational model used the actual as operated hull form. It will be shown that using a hybrid RANS-BEM method, the predicted ship speeds at selfpropulsion are over-estimated by 0.17-0.28 knots compared to the trial data. The various aspects that influence the accuracy of the direct prediction of power and RPM using CFD are critically discussed.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Blind self-propulsion predictions for the 2016 LR Workshop on Ship Scale Hydrodynamic Computer Simulation have been carried out to simulate the full scale performance of a self-propelled ship in ballast. The single screw ship of 11542 tonnes had been scanned in drydock so the computational model used the actual as operated hull form. It will be shown that using a hybrid RANS-BEM method, the predicted ship speeds at selfpropulsion are over-estimated by 0.17-0.28 knots compared to the trial data. The various aspects that influence the accuracy of the direct prediction of power and RPM using CFD are critically discussed.
5.
Crepier, P.
Ship Resistance Prediction: Verification And Validation Exercise On Unstructured Grids Conference
VII International Conference on Computational Methods in Marine Engineering (MARINE2017), 2017.
@conference{Crepier2017,
title = {Ship Resistance Prediction: Verification And Validation Exercise On Unstructured Grids},
author = {Crepier, P.},
url = {http://www.marin.nl/web/Publications/Publication-items/Ship-Resistance-Prediction-Verification-And-Validation-Exercise-On-Unstructured-Grids.htm},
year = {2017},
date = {2017-05-01},
booktitle = {VII International Conference on Computational Methods in Marine Engineering (MARINE2017)},
abstract = {The prediction of the resistance of a ship is, together with the propeller performance prediction, part of the key aspects during the design process of a ship, as it partly ensures the quality of the power-prediction. Body fitted structured grids for ship simulations can be rather challenging and time consuming to build, especially when dealing with appended ship geometries. For this reason, unstructured hexahedral trimmed grids are more and more used. Such grids can be build by various CFD package such as CD-Adapcos Star CCM+, NUMECAs Hexpress grid generator or OpenFOAMSs SnappyHexMesh. Although their use is increasing or even already adopted, the numerical uncertainty of these simulations seems to be a well-kept secret.
In the study presented, an attempt at quantifying the numerical uncertainty of the resistance for the combination of the RANS Solver ReFRESCO [1] with grids generated using the commercial package Hexpress is made. The studied case is the flow around the bare-hull KVLCC2 at model scale Reynolds number. Extensive verification and validation on the same test case has already been published for the combination of ReFRESCO and structured grids by Pereira et al. [2].
The method to generate grids as geometrically similar as possible is presented, and the uncertainty analysis by L. Ec¸a and M. Hoekstra [3] is performed on the integral results obtained.
The simulations are performed using the k − ω SST, k − ω TNT and the k −√kL turbulence models. The velocity fields calculated in the propeller plane are compared to the measured ones and to the results obtained by Pereira et al. [2] on structured grids.
The results show that the differences with the experimental results are in the same range as the differences obtained with structured grids. The numerical uncertainties are, however, higher. They are also strongly dependent on the turbulence model used, like for structured grids, and are spread between 1.3% and 12%.
Concerning the wake flow details, not all features present in the experimental results are obtained and, compared to structured grids, the flow features are smoothed. The wake flow is also influenced by the turbulence modelling and needs to be adressed in more detail.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
The prediction of the resistance of a ship is, together with the propeller performance prediction, part of the key aspects during the design process of a ship, as it partly ensures the quality of the power-prediction. Body fitted structured grids for ship simulations can be rather challenging and time consuming to build, especially when dealing with appended ship geometries. For this reason, unstructured hexahedral trimmed grids are more and more used. Such grids can be build by various CFD package such as CD-Adapcos Star CCM+, NUMECAs Hexpress grid generator or OpenFOAMSs SnappyHexMesh. Although their use is increasing or even already adopted, the numerical uncertainty of these simulations seems to be a well-kept secret.
In the study presented, an attempt at quantifying the numerical uncertainty of the resistance for the combination of the RANS Solver ReFRESCO [1] with grids generated using the commercial package Hexpress is made. The studied case is the flow around the bare-hull KVLCC2 at model scale Reynolds number. Extensive verification and validation on the same test case has already been published for the combination of ReFRESCO and structured grids by Pereira et al. [2].
The method to generate grids as geometrically similar as possible is presented, and the uncertainty analysis by L. Ec¸a and M. Hoekstra [3] is performed on the integral results obtained.
The simulations are performed using the k − ω SST, k − ω TNT and the k −√kL turbulence models. The velocity fields calculated in the propeller plane are compared to the measured ones and to the results obtained by Pereira et al. [2] on structured grids.
The results show that the differences with the experimental results are in the same range as the differences obtained with structured grids. The numerical uncertainties are, however, higher. They are also strongly dependent on the turbulence model used, like for structured grids, and are spread between 1.3% and 12%.
Concerning the wake flow details, not all features present in the experimental results are obtained and, compared to structured grids, the flow features are smoothed. The wake flow is also influenced by the turbulence modelling and needs to be adressed in more detail.
In the study presented, an attempt at quantifying the numerical uncertainty of the resistance for the combination of the RANS Solver ReFRESCO [1] with grids generated using the commercial package Hexpress is made. The studied case is the flow around the bare-hull KVLCC2 at model scale Reynolds number. Extensive verification and validation on the same test case has already been published for the combination of ReFRESCO and structured grids by Pereira et al. [2].
The method to generate grids as geometrically similar as possible is presented, and the uncertainty analysis by L. Ec¸a and M. Hoekstra [3] is performed on the integral results obtained.
The simulations are performed using the k − ω SST, k − ω TNT and the k −√kL turbulence models. The velocity fields calculated in the propeller plane are compared to the measured ones and to the results obtained by Pereira et al. [2] on structured grids.
The results show that the differences with the experimental results are in the same range as the differences obtained with structured grids. The numerical uncertainties are, however, higher. They are also strongly dependent on the turbulence model used, like for structured grids, and are spread between 1.3% and 12%.
Concerning the wake flow details, not all features present in the experimental results are obtained and, compared to structured grids, the flow features are smoothed. The wake flow is also influenced by the turbulence modelling and needs to be adressed in more detail.
6.
Christian; Gornicz Veldhuis, Tomasz; Scholcz
13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark, no. ID080, Practical Design of Ships and Other Floating Structures 2016.
@conference{Veldhuis2016,
title = {Ship optimization using viscous flow computations in combination with generic shape variations and Design of Experiments},
author = {Veldhuis, Christian; Gornicz, Tomasz; Scholcz, Thomas},
url = {http://www.marin.nl/web/Publications/Papers/Ship-optimization-using-viscous-flow-computations-in-combination-with-generic-shape-variations-and-Design-of-Experiments.htm},
year = {2016},
date = {2016-09-04},
booktitle = {13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark},
journal = {Proceedings of PRADS2016 4th – 8th September, 2016 Copenhagen, Denmark},
number = {ID080},
organization = {Practical Design of Ships and Other Floating Structures},
abstract = {This paper discusses a procedure to optimize ship hull forms for minimum required power and best wake field quality, based on viscous flow computations. This research elaborates on an earlier optimization at MARIN (Van der Ploeg and Raven, 2010 and Van der Ploeg, Starke and Veldhuis, 2013). That optimization lead to a clear Pareto front and trends for a systematic variation study for the afterbody of a chemical tanker. In 2016, new steps are taken to ease and generalize the method of hull shape generation. In the previous study the design space was set up by means of ‘manually’ designed basis hull shapes. In the new approach we test the use of generic basis hull shapes which are automatically generated from one initial hull shape. If effective, this approach can speed up the design process significantly. Finally, we want to improve the process even further by using a Design of Exper-iments approach in which the systematic variations are re-placed by a more clever distribution of calculations over the design space. },
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
This paper discusses a procedure to optimize ship hull forms for minimum required power and best wake field quality, based on viscous flow computations. This research elaborates on an earlier optimization at MARIN (Van der Ploeg and Raven, 2010 and Van der Ploeg, Starke and Veldhuis, 2013). That optimization lead to a clear Pareto front and trends for a systematic variation study for the afterbody of a chemical tanker. In 2016, new steps are taken to ease and generalize the method of hull shape generation. In the previous study the design space was set up by means of ‘manually’ designed basis hull shapes. In the new approach we test the use of generic basis hull shapes which are automatically generated from one initial hull shape. If effective, this approach can speed up the design process significantly. Finally, we want to improve the process even further by using a Design of Exper-iments approach in which the systematic variations are re-placed by a more clever distribution of calculations over the design space.
7.
Tomasz; van der Ploeg Gornics, Auke; Scholcz
Trim wedge optimization with viscous free surface computations Conference
Proceedings of PRADS2016, Copenhagen, Denmark, 2016.
@conference{Gornics2016,
title = {Trim wedge optimization with viscous free surface computations},
author = {Gornics, Tomasz; van der Ploeg, Auke; Scholcz, Thomas},
url = {http://www.marin.nl/web/Publications/Papers/Trim-wedge-optimization-with-viscous-free-surface-computations.htm},
year = {2016},
date = {2016-09-04},
booktitle = {Proceedings of PRADS2016, Copenhagen, Denmark},
abstract = {A procedure for automatic optimization of a ship hull and
trim wedge is described, that is based on an evaluation
of a series of hull form/trim wedge combinations. These
evaluations are done with a RANS method that can accurately
and efficiently compute the viscous flow for several
transom flow regimes, ranging from completely dry
to (partly) wetted. The object function is an approximation
of the required power to maintain a given speed. Results
obtained from several trim wedge optimizations are
shown, computed and measured trends are compared and
computed scale effects in those trends are discussed. For
two examples, a considerable improvement of the object
function can be obtained. At full scale, the improvement
of the object function is stronger than at model scale.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
A procedure for automatic optimization of a ship hull and
trim wedge is described, that is based on an evaluation
of a series of hull form/trim wedge combinations. These
evaluations are done with a RANS method that can accurately
and efficiently compute the viscous flow for several
transom flow regimes, ranging from completely dry
to (partly) wetted. The object function is an approximation
of the required power to maintain a given speed. Results
obtained from several trim wedge optimizations are
shown, computed and measured trends are compared and
computed scale effects in those trends are discussed. For
two examples, a considerable improvement of the object
function can be obtained. At full scale, the improvement
of the object function is stronger than at model scale.
trim wedge is described, that is based on an evaluation
of a series of hull form/trim wedge combinations. These
evaluations are done with a RANS method that can accurately
and efficiently compute the viscous flow for several
transom flow regimes, ranging from completely dry
to (partly) wetted. The object function is an approximation
of the required power to maintain a given speed. Results
obtained from several trim wedge optimizations are
shown, computed and measured trends are compared and
computed scale effects in those trends are discussed. For
two examples, a considerable improvement of the object
function can be obtained. At full scale, the improvement
of the object function is stronger than at model scale.
8.
M. Kerkvliet, Carette; Straten, O. van
Analysis of free surface anti-roll tank using URANS. Verification and validation Conference
13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark, 2016.
@conference{Kerkvliet2016,
title = {Analysis of free surface anti-roll tank using URANS. Verification and validation},
author = {Kerkvliet, M., Carette, N. and Straten, O. van},
url = {http://www.marin.nl/web/Publications/Papers/Analysis-of-free-surface-antiroll-tank-using-URANS.-Verification-and-validation-1.htm},
year = {2016},
date = {2016-09-04},
booktitle = {13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark},
pages = {ID055},
abstract = {To prevent excessive roll motion of ships operating in seas, damping systems are often required. Exterior systems can be used like, bilge keels or active stabilizer fins, or interior systems like anti-roll tanks (ARTs). There are mainly two sorts of ARTs, i.e. free surface tanks and Utype tanks. Both types have been studied extensively in the past, e.g. by Watts (1883), Frahm (1911) and Verhagen and Wijngaarden (1965), but also more recently, e.g. by Lee and Vassalos (1996), Kerkvliet et al. (2014) and Carette (2015). The content of this paper is restricted to the free surface type ART, which is nowadays often used to increase the roll damping of ships passively. The main advantages of such an ART are the large damping moment at small roll amplitudes and the ease to adapt the response by changing the water level. The response of the tank is highly frequency and amplitude dependent with a strong non-linear character (Carette et al., 2016). Also the shape of the interior geometry, e.g. additional struts, plates or other flow obstructions, will have an effect on the response, which makes it difficult to predict the response by analytical models. Therefore, systematic oscillation tests are often performed by model-scale experiments or by use of Computational Fluid Dynamics (CFD). This paper shows the response of a two-dimensional (2D) and three-dimensional (3D) model-scale free surface ART using the CFD code ReFRESCO (www.refresco.org). The objective of this paper is to show which issues are important when CFD is used as a research and design tool. A verification and validation study is performed to determine numerical settings to obtain a good trade-off between accuracy and computational costs. The CFD results are validated against model-scale experimental results, based on the work of Carette (2015). The results show that CFD can be used as a simulation driven design tool to accurately predict the response of an ART.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
To prevent excessive roll motion of ships operating in seas, damping systems are often required. Exterior systems can be used like, bilge keels or active stabilizer fins, or interior systems like anti-roll tanks (ARTs). There are mainly two sorts of ARTs, i.e. free surface tanks and Utype tanks. Both types have been studied extensively in the past, e.g. by Watts (1883), Frahm (1911) and Verhagen and Wijngaarden (1965), but also more recently, e.g. by Lee and Vassalos (1996), Kerkvliet et al. (2014) and Carette (2015). The content of this paper is restricted to the free surface type ART, which is nowadays often used to increase the roll damping of ships passively. The main advantages of such an ART are the large damping moment at small roll amplitudes and the ease to adapt the response by changing the water level. The response of the tank is highly frequency and amplitude dependent with a strong non-linear character (Carette et al., 2016). Also the shape of the interior geometry, e.g. additional struts, plates or other flow obstructions, will have an effect on the response, which makes it difficult to predict the response by analytical models. Therefore, systematic oscillation tests are often performed by model-scale experiments or by use of Computational Fluid Dynamics (CFD). This paper shows the response of a two-dimensional (2D) and three-dimensional (3D) model-scale free surface ART using the CFD code ReFRESCO (www.refresco.org). The objective of this paper is to show which issues are important when CFD is used as a research and design tool. A verification and validation study is performed to determine numerical settings to obtain a good trade-off between accuracy and computational costs. The CFD results are validated against model-scale experimental results, based on the work of Carette (2015). The results show that CFD can be used as a simulation driven design tool to accurately predict the response of an ART.
9.
L. Eça, Vaz; Abreu, H.
Validation: What, Why And How Conference
OMAE ASME 35th International Conference on Ocean, Offshore and Arctic Engineering, Busan, South Korea, 2016.
@conference{Eça2016,
title = {Validation: What, Why And How},
author = {Eça, L., Vaz, G., Koop, A., Pereira, F. and Abreu, H.},
url = {http://www.marin.nl/web/Publications/Papers/Validation-What-Why-And-How.htm},
year = {2016},
date = {2016-06-19},
booktitle = {OMAE ASME 35th International Conference on Ocean, Offshore and Arctic Engineering, Busan, South Korea},
pages = {OMAE2016-54005},
abstract = {Offshore and Naval engineering have relied on physical models, i.e. experimental fluid dynamics (EFD), for several decades. Although the role of experiments in engineering is still unquestionable, some of the limitations of physical models, as for example domain size (blockage and scale effects), can be addressed using mathematical models, i.e. computational fluid dynamics (CFD). However, to gain confidence in the use of CFD it is fundamental to determine the modelling accuracy, i.e. to determine the difference between the “physical reality” and the selected mathematical model. The quantification of the modelling error is the goal of Validation. It must be emphasized that Validation applies to the mathematical model (and not the code) and is performed for selected flow quantities (the so-called quantities of interest).
Ideally, Validation would be performed comparing an exact measurement of the “physical reality” with the exact solution of the selected mathematical model. However, exact measurements do not exist and mathematical models for turbulent flows do not have analytical solutions. Therefore, procedures must be developed to take into account experimental and numerical uncertainties. Furthermore, the exact values of the flow parameters as for example Reynolds number, fluid viscosity or inlet turbulence quantities are often unknown, which leads to the so-called parameter uncertainty that also has to be dealt within the assessment of the modelling error.
The main goal of this paper is to demonstrate that the very popular designation of ”code X is validated” is meaningless without saying what is the mathematical model embedded in the code, what are the quantities of interest for the specific application and what is the Validation uncertainty imposed by the experimental, numerical and parameter uncertainties. Furthermore, we also illustrate that Validation is not a pass or fail exercise. A modelling error of 10% may be acceptable for a given application, whereas 1% may not be enough for a different one.
To this end, we present the application of the ASME V&V 20 Validation procedure for local set points and the metric for multiple set points to several practical test cases: prediction of transition from laminar to turbulent regime for the flow over a flat plate; flow around a circular cylinder; flow around the KVLCC2 tanker and current loads in shallow water for a LNG carrier. In most of these exercises, parameter uncertainty is assumed to be zero, which is an assumption often required for the so-called practical calculations due to the computational effort required to address it. Nonetheless, as an illustration of its application, the flow over the flat plate includes parameter uncertainty for the specification of the inlet turbulence quantities.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Offshore and Naval engineering have relied on physical models, i.e. experimental fluid dynamics (EFD), for several decades. Although the role of experiments in engineering is still unquestionable, some of the limitations of physical models, as for example domain size (blockage and scale effects), can be addressed using mathematical models, i.e. computational fluid dynamics (CFD). However, to gain confidence in the use of CFD it is fundamental to determine the modelling accuracy, i.e. to determine the difference between the “physical reality” and the selected mathematical model. The quantification of the modelling error is the goal of Validation. It must be emphasized that Validation applies to the mathematical model (and not the code) and is performed for selected flow quantities (the so-called quantities of interest).
Ideally, Validation would be performed comparing an exact measurement of the “physical reality” with the exact solution of the selected mathematical model. However, exact measurements do not exist and mathematical models for turbulent flows do not have analytical solutions. Therefore, procedures must be developed to take into account experimental and numerical uncertainties. Furthermore, the exact values of the flow parameters as for example Reynolds number, fluid viscosity or inlet turbulence quantities are often unknown, which leads to the so-called parameter uncertainty that also has to be dealt within the assessment of the modelling error.
The main goal of this paper is to demonstrate that the very popular designation of ”code X is validated” is meaningless without saying what is the mathematical model embedded in the code, what are the quantities of interest for the specific application and what is the Validation uncertainty imposed by the experimental, numerical and parameter uncertainties. Furthermore, we also illustrate that Validation is not a pass or fail exercise. A modelling error of 10% may be acceptable for a given application, whereas 1% may not be enough for a different one.
To this end, we present the application of the ASME V&V 20 Validation procedure for local set points and the metric for multiple set points to several practical test cases: prediction of transition from laminar to turbulent regime for the flow over a flat plate; flow around a circular cylinder; flow around the KVLCC2 tanker and current loads in shallow water for a LNG carrier. In most of these exercises, parameter uncertainty is assumed to be zero, which is an assumption often required for the so-called practical calculations due to the computational effort required to address it. Nonetheless, as an illustration of its application, the flow over the flat plate includes parameter uncertainty for the specification of the inlet turbulence quantities.
Ideally, Validation would be performed comparing an exact measurement of the “physical reality” with the exact solution of the selected mathematical model. However, exact measurements do not exist and mathematical models for turbulent flows do not have analytical solutions. Therefore, procedures must be developed to take into account experimental and numerical uncertainties. Furthermore, the exact values of the flow parameters as for example Reynolds number, fluid viscosity or inlet turbulence quantities are often unknown, which leads to the so-called parameter uncertainty that also has to be dealt within the assessment of the modelling error.
The main goal of this paper is to demonstrate that the very popular designation of ”code X is validated” is meaningless without saying what is the mathematical model embedded in the code, what are the quantities of interest for the specific application and what is the Validation uncertainty imposed by the experimental, numerical and parameter uncertainties. Furthermore, we also illustrate that Validation is not a pass or fail exercise. A modelling error of 10% may be acceptable for a given application, whereas 1% may not be enough for a different one.
To this end, we present the application of the ASME V&V 20 Validation procedure for local set points and the metric for multiple set points to several practical test cases: prediction of transition from laminar to turbulent regime for the flow over a flat plate; flow around a circular cylinder; flow around the KVLCC2 tanker and current loads in shallow water for a LNG carrier. In most of these exercises, parameter uncertainty is assumed to be zero, which is an assumption often required for the so-called practical calculations due to the computational effort required to address it. Nonetheless, as an illustration of its application, the flow over the flat plate includes parameter uncertainty for the specification of the inlet turbulence quantities.
10.
Toxopeus, S. L.; Bhawsinka, K.
Calculation of hydrodynamic interaction forces on a ship entering a Lock using CFD Conference
Fourth International Conference on Ship Manoeuvring in Shallow and Confined Water (MASHCON) - Ship Bottom Interaction, Hamburg, Germany, 2016.
@conference{Toxopeus2016,
title = {Calculation of hydrodynamic interaction forces on a ship entering a Lock using CFD},
author = {Toxopeus, S.L. and Bhawsinka, K.},
url = {http://www.marin.nl/web/Publications/Papers/Calculation-of-hydrodynamic-interaction-forces-on-a-ship-entering-a-Lock-using-CFD.htm},
doi = {10.18451/978-3-939230-38-0_34},
year = {2016},
date = {2016-05-01},
booktitle = {Fourth International Conference on Ship Manoeuvring in Shallow and Confined Water (MASHCON) - Ship Bottom Interaction, Hamburg, Germany},
pages = {6_01},
abstract = {Estimation of hydrodynamic interaction forces experienced by a ship entering a lock plays an important role in the initial design phase of the lock. These forces govern the speed at which a ship can enter the lock and also the tug requirement for facilitating such manoeuvres. Hence hydrodynamic interaction forces can influence the turnaround time and the operational cost of the locks. Traditionally these forces have been calculated using model tests or by potential flow solvers.
In this paper, a study is presented on predicting ship-lock interaction effects with the viscous-flow solver ReFRESCO. The scenario consists of a large-beam bulk carrier entering the Pierre Vandamme Lock in Zeebrugge, Belgium. To validate the predictions, existing model tests are used. Furthermore, the results are compared to potential flow computations and CFD results from literature to highlight the benefits of each approach.
The paper will show that with careful setup of the computations, reliable predictions of the ship-lock interaction effects can be obtained. In order to capture all physics of the interaction, viscous-flow computations are preferred above potential-flow predictions.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Estimation of hydrodynamic interaction forces experienced by a ship entering a lock plays an important role in the initial design phase of the lock. These forces govern the speed at which a ship can enter the lock and also the tug requirement for facilitating such manoeuvres. Hence hydrodynamic interaction forces can influence the turnaround time and the operational cost of the locks. Traditionally these forces have been calculated using model tests or by potential flow solvers.
In this paper, a study is presented on predicting ship-lock interaction effects with the viscous-flow solver ReFRESCO. The scenario consists of a large-beam bulk carrier entering the Pierre Vandamme Lock in Zeebrugge, Belgium. To validate the predictions, existing model tests are used. Furthermore, the results are compared to potential flow computations and CFD results from literature to highlight the benefits of each approach.
The paper will show that with careful setup of the computations, reliable predictions of the ship-lock interaction effects can be obtained. In order to capture all physics of the interaction, viscous-flow computations are preferred above potential-flow predictions.
In this paper, a study is presented on predicting ship-lock interaction effects with the viscous-flow solver ReFRESCO. The scenario consists of a large-beam bulk carrier entering the Pierre Vandamme Lock in Zeebrugge, Belgium. To validate the predictions, existing model tests are used. Furthermore, the results are compared to potential flow computations and CFD results from literature to highlight the benefits of each approach.
The paper will show that with careful setup of the computations, reliable predictions of the ship-lock interaction effects can be obtained. In order to capture all physics of the interaction, viscous-flow computations are preferred above potential-flow predictions.
11.
Henk; Flikkema Prins, Maarten; Schuiling
Green retrofitting through optimisation of hull-propulsion interaction - GRIP Conference
Proceedings of 6th Transport Research Arena, Warsaw, Poland, 2016.
@conference{Prins2016,
title = {Green retrofitting through optimisation of hull-propulsion interaction - GRIP},
author = {Prins, Henk; Flikkema, Maarten; Schuiling, Bart; Xing-Kaeding, Y; Voermans, A. A. M.; Müller, M; Coache, S; Hasselaar, Thijs; Paboeuf, S},
url = {http://www.marin.nl/web/Publications/Papers/Green-retrofitting-through-optimisation-of-hullpropulsion-interaction-GRIP.htm },
year = {2016},
date = {2016-04-18},
booktitle = {Proceedings of 6th Transport Research Arena, Warsaw, Poland},
abstract = {In the FP7 project GRIP, partners have extensively studied Energy Saving Devices which improve the propulsive efficiency of ships. The research has focussed on an early assessment of the performance, yard processes for the installation of an ESD, structural issues related to ESDs, and the hydrodynamical working principles of ESDs. All the work came together in the final demonstration of the efficiency gain of an ESD on Uljanik built bulk carrier MV Valvoline.
To demonstrate the ESD design procedure and the potential performance gain of ESDs, a design competition was held between MARIN, HSVA and Vicus who designed a pre-duct, pre-swirl stator and rudder bulb respectively. Designs were evaluated based on the performance improvement, manufacturability and structural issues. The PSS designed by HSVA came out the best with a reduction of required propulsion power. CFD analysis has shown that the PSS creates a pre-swirl resulting in an increase of the propeller efficiency mainly affecting the upcoming blade trajectory. Speed trial procedures were evaluated by MARIN to come to a procedure to evaluate the performance change with a minimum uncertainty. Speed trials before and after installation of the PSS on the bulk carrier were performed in favourable environmental conditions resulting in a performance improvement of 6.8% at a speed of 16 knots.
This paper gives an overview of the work performed in the project by all partners resulting in the successful demonstration.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
In the FP7 project GRIP, partners have extensively studied Energy Saving Devices which improve the propulsive efficiency of ships. The research has focussed on an early assessment of the performance, yard processes for the installation of an ESD, structural issues related to ESDs, and the hydrodynamical working principles of ESDs. All the work came together in the final demonstration of the efficiency gain of an ESD on Uljanik built bulk carrier MV Valvoline.
To demonstrate the ESD design procedure and the potential performance gain of ESDs, a design competition was held between MARIN, HSVA and Vicus who designed a pre-duct, pre-swirl stator and rudder bulb respectively. Designs were evaluated based on the performance improvement, manufacturability and structural issues. The PSS designed by HSVA came out the best with a reduction of required propulsion power. CFD analysis has shown that the PSS creates a pre-swirl resulting in an increase of the propeller efficiency mainly affecting the upcoming blade trajectory. Speed trial procedures were evaluated by MARIN to come to a procedure to evaluate the performance change with a minimum uncertainty. Speed trials before and after installation of the PSS on the bulk carrier were performed in favourable environmental conditions resulting in a performance improvement of 6.8% at a speed of 16 knots.
This paper gives an overview of the work performed in the project by all partners resulting in the successful demonstration.
To demonstrate the ESD design procedure and the potential performance gain of ESDs, a design competition was held between MARIN, HSVA and Vicus who designed a pre-duct, pre-swirl stator and rudder bulb respectively. Designs were evaluated based on the performance improvement, manufacturability and structural issues. The PSS designed by HSVA came out the best with a reduction of required propulsion power. CFD analysis has shown that the PSS creates a pre-swirl resulting in an increase of the propeller efficiency mainly affecting the upcoming blade trajectory. Speed trial procedures were evaluated by MARIN to come to a procedure to evaluate the performance change with a minimum uncertainty. Speed trials before and after installation of the PSS on the bulk carrier were performed in favourable environmental conditions resulting in a performance improvement of 6.8% at a speed of 16 knots.
This paper gives an overview of the work performed in the project by all partners resulting in the successful demonstration.
12.
Starke, Bram
A Workshop on CFD in Ship Hydrodynamics, Tokyo, Japan, no. 15-2, Tokyo 2015, 2015.
@conference{Starke2015,
title = {Viscous Free-Surface Power Predictions For Self-Propulsion Using A Hybrid RANS-BEM Coupling Procedure (PARNASSOS-PROCAL)},
author = {Bram Starke},
url = {http://www.marin.nl/web/Publications/Papers/Viscous-FreeSurface-Power-Predictions-For-SelfPropulsion-Using-A-Hybrid-RANSBEM-Coupling-Procedure-PARNASSOSPROCAL.htm},
year = {2015},
date = {2015-12-01},
booktitle = {A Workshop on CFD in Ship Hydrodynamics, Tokyo, Japan},
journal = {Tokyo 2015, A Workshop on CFD in Ship Hydrodynamics, Tokyo, Japan},
number = {15-2},
publisher = {Tokyo 2015},
abstract = {This paper presents results of computations for the 2015 CFD workshop in Tokyo. It briefly describes the RANS method used, the particular treatment of the free surface boundary conditions, and the coupling between the steady RANS code and a boundary element method used for the propeller analysis. Computations for the KCS (case 2.5) have been performed at five grids with different densities. It will be shown that mesh dependence of thrust, torque and RPM at the finest meshes is small, with comparison errors of approximately -0.3 per cent for the resistance, -1.8 per cent for RPM, +3.5 for KT and +5.9 per cent for KQ. The corresponding error estimation results in uncertainties of less than 1 per cent for the powering parameters, but this value may be too optimistic as a result on at least one more grid has to be generated to perform the uncertainty estimation correctly.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
This paper presents results of computations for the 2015 CFD workshop in Tokyo. It briefly describes the RANS method used, the particular treatment of the free surface boundary conditions, and the coupling between the steady RANS code and a boundary element method used for the propeller analysis. Computations for the KCS (case 2.5) have been performed at five grids with different densities. It will be shown that mesh dependence of thrust, torque and RPM at the finest meshes is small, with comparison errors of approximately -0.3 per cent for the resistance, -1.8 per cent for RPM, +3.5 for KT and +5.9 per cent for KQ. The corresponding error estimation results in uncertainties of less than 1 per cent for the powering parameters, but this value may be too optimistic as a result on at least one more grid has to be generated to perform the uncertainty estimation correctly.
13.
Prins, Henk
MARIN invests in the future as CFD takes on more prominent role Journal Article
In: MARIN Report, no. 115, pp. 12-13, 2015.
@article{Prins2015,
title = {MARIN invests in the future as CFD takes on more prominent role},
author = {Henk Prins},
url = {http://content.yudu.com/web/1r3p1/0A3a046/MR115/html/index.html?page=12},
year = {2015},
date = {2015-08-01},
journal = {MARIN Report},
number = {115},
pages = {12-13},
abstract = {To facilitate the use of reliable CFD in the design and engineering process, MARIN has invested in a new, large computer cluster, and is sharing its CFD code ReFRESCO with its customers.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
To facilitate the use of reliable CFD in the design and engineering process, MARIN has invested in a new, large computer cluster, and is sharing its CFD code ReFRESCO with its customers.
14.
Dang, Jie; Chen, Hao; Rueda, Luis; Willemsen, Harry
Fourth International Symposium on Marine Propulsors (SMP), Austin, Texas , Symposiums on Marine Propulsors 2015.
@conference{Dang2015,
title = {Integrated Design of Asymmetric Aftbody and Propeller for an Aframax Tanker to Maximize Energy Efficiency},
author = {Jie Dang and Hao Chen and Luis Rueda and Harry Willemsen},
url = {http://www.marin.nl/web/Publications/Papers/Integrated-Design-of-Asymmetric-Aftbody-and-Propeller-for-an-Aframax-Tanker-to-Maximize-Energy-Efficiency.htm
http://www.marinepropulsors.com/proceedings.php},
year = {2015},
date = {2015-06-01},
booktitle = {Fourth International Symposium on Marine Propulsors (SMP), Austin, Texas },
organization = {Symposiums on Marine Propulsors},
abstract = {With the implementation of the EEDI, energy saving and emission reduction of ships, especially merchant ships, become more and more important. To achieve high efficiency and low emissions, recently Energy Saving Devices (ESDs) have been re-studied and installed to many ships, both new buildings and also retrofits. Various ESDs, including new concepts, have been tested in model scale and large improvements on energy efficiency have been confirmed. However due to the fact that most ESDs are fitted in the wake field, the performance of the ESDs is influenced by scale effects. For the operators, the fouling and the structure integration of the ESD’s with the hull are the important issues to make decisions on applying ESDs to their ships.
Distinguished from the ESDs where extra ‘appendages’ have to be added in front of and/or behind a propeller, an asymmetric aftbody can also change the flow towards the propeller without appendages. The wake with pre-swirl generated by an asymmetric aftbody is in general more uniform than that by an ESD (such as a pre-stator with finite blades) and with almost no penalty on the ship’s resistance. By integrating a propeller, a ship with asymmetric aftbody can be designed so that the hull-propeller interaction is optimized for its total propulsive efficiency and the required shaft power is minimized at given speed.
In this paper, discussions have been given on the optimization procedure by using the Computational Fluid Dynamics (CFD) towards a fully-integrated hull-propeller design to maximize the energy efficiency of a single screw ship. Comparative model tests, carried out with optimized symmetric and asymmetric ships, showed more than 6% gain in efficiency with a moderate asymmetric aftbody, without detriments to its course stability. },
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
With the implementation of the EEDI, energy saving and emission reduction of ships, especially merchant ships, become more and more important. To achieve high efficiency and low emissions, recently Energy Saving Devices (ESDs) have been re-studied and installed to many ships, both new buildings and also retrofits. Various ESDs, including new concepts, have been tested in model scale and large improvements on energy efficiency have been confirmed. However due to the fact that most ESDs are fitted in the wake field, the performance of the ESDs is influenced by scale effects. For the operators, the fouling and the structure integration of the ESD’s with the hull are the important issues to make decisions on applying ESDs to their ships.
Distinguished from the ESDs where extra ‘appendages’ have to be added in front of and/or behind a propeller, an asymmetric aftbody can also change the flow towards the propeller without appendages. The wake with pre-swirl generated by an asymmetric aftbody is in general more uniform than that by an ESD (such as a pre-stator with finite blades) and with almost no penalty on the ship’s resistance. By integrating a propeller, a ship with asymmetric aftbody can be designed so that the hull-propeller interaction is optimized for its total propulsive efficiency and the required shaft power is minimized at given speed.
In this paper, discussions have been given on the optimization procedure by using the Computational Fluid Dynamics (CFD) towards a fully-integrated hull-propeller design to maximize the energy efficiency of a single screw ship. Comparative model tests, carried out with optimized symmetric and asymmetric ships, showed more than 6% gain in efficiency with a moderate asymmetric aftbody, without detriments to its course stability.
Distinguished from the ESDs where extra ‘appendages’ have to be added in front of and/or behind a propeller, an asymmetric aftbody can also change the flow towards the propeller without appendages. The wake with pre-swirl generated by an asymmetric aftbody is in general more uniform than that by an ESD (such as a pre-stator with finite blades) and with almost no penalty on the ship’s resistance. By integrating a propeller, a ship with asymmetric aftbody can be designed so that the hull-propeller interaction is optimized for its total propulsive efficiency and the required shaft power is minimized at given speed.
In this paper, discussions have been given on the optimization procedure by using the Computational Fluid Dynamics (CFD) towards a fully-integrated hull-propeller design to maximize the energy efficiency of a single screw ship. Comparative model tests, carried out with optimized symmetric and asymmetric ships, showed more than 6% gain in efficiency with a moderate asymmetric aftbody, without detriments to its course stability.
15.
van der Meij, Karola; Raven, Hoyte
Promising hydrodynamic improvements for inland vessels Conference
EIWN Conference, Budapest, Hungary, European Inland Waterway Navigation Conference , 2014.
@conference{Meij2014,
title = {Promising hydrodynamic improvements for inland vessels},
author = {Karola van der Meij and Hoyte Raven},
url = {http://www.marin.nl/web/Publications/Publication-items/Promising-Hydrodynamic-Improvements-for-Inland-Vessels-1.htm
},
year = {2014},
date = {2014-09-10},
booktitle = {EIWN Conference, Budapest, Hungary},
publisher = {European Inland Waterway Navigation Conference },
abstract = {In the EU project Move IT! and the Joint Industry Project SAVE, extensive CFD calculations have been performed for several existing inland vessels. The objective was to investigate possible retrofit options to improve the hydrodynamic performance, and to determine the potential reduction in fuel consumption. This paper presents the results of the CFD calculations performed for the vessels. Different bow shapes have been analysed and a detailed investigation was performed on the shape of the aftship, especially focussing on the tunnel design. Some of the improvements were very promising and provide an interesting basis for inland ship design in general.
},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
In the EU project Move IT! and the Joint Industry Project SAVE, extensive CFD calculations have been performed for several existing inland vessels. The objective was to investigate possible retrofit options to improve the hydrodynamic performance, and to determine the potential reduction in fuel consumption. This paper presents the results of the CFD calculations performed for the vessels. Different bow shapes have been analysed and a detailed investigation was performed on the shape of the aftship, especially focussing on the tunnel design. Some of the improvements were very promising and provide an interesting basis for inland ship design in general.
16.
van der Ploeg, Auke; Starke, Bram; Veldhuis, Christian
Optimization of a Chemical Tanker with Free-surface Viscous Flow Computations Conference
Proceedings of the PRADS2013, CECO, Changwon City, Korea, no. 096, Practical Design of Ships and Other Floating Structures 2013.
@conference{Ploeg2013,
title = {Optimization of a Chemical Tanker with Free-surface Viscous Flow Computations},
author = {Auke van der Ploeg and Bram Starke and Christian Veldhuis},
url = {http://www.marin.nl/web/Publications/Papers/Optimization-of-a-Chemical-Tanker-with-Freesurface-Viscous-Flow-Computations.htm},
year = {2013},
date = {2013-10-01},
booktitle = {Proceedings of the PRADS2013, CECO, Changwon City, Korea},
journal = {Proceedigs of the PRADS 2013},
number = {096},
organization = {Practical Design of Ships and Other Floating Structures},
abstract = {This paper discusses a procedure to optimize ship hull forms for minimum required power and best wake field quality, based on CFD computations of the viscous flow. A flexible and effective definition of parametric hull form variations is used, based on interpolation between basis hull forms. All RANS computations were performed for full-scale Reynolds number. An initial optimization has been obtained neglecting the ship’s wave making. Clear Pareto fronts and trends in the solutions are obtained in a systematic variation study for the afterbody of a chemical tanker. In addition we performed a systematic variation using RANS free surface, to study the influence of wave making on the computed trends. As a result, a further decrease in the object functions could be obtained and another hull form appeared to be optimal.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
This paper discusses a procedure to optimize ship hull forms for minimum required power and best wake field quality, based on CFD computations of the viscous flow. A flexible and effective definition of parametric hull form variations is used, based on interpolation between basis hull forms. All RANS computations were performed for full-scale Reynolds number. An initial optimization has been obtained neglecting the ship’s wave making. Clear Pareto fronts and trends in the solutions are obtained in a systematic variation study for the afterbody of a chemical tanker. In addition we performed a systematic variation using RANS free surface, to study the influence of wave making on the computed trends. As a result, a further decrease in the object functions could be obtained and another hull form appeared to be optimal.
17.
Schuiling, Bart; vaz, Guilherme
ReFRESCO plays major role in understanding and designing Energy Saving Devices Journal Article
In: MARIN Report, no. 109, pp. 14-15, 2013.
@article{Schuiling2013,
title = {ReFRESCO plays major role in understanding and designing Energy Saving Devices},
author = {Bart Schuiling and Guilherme vaz},
url = {http://www.marin.nl/extra/marin-bladermodules/html/109/#14},
year = {2013},
date = {2013-08-01},
journal = {MARIN Report},
number = {109},
pages = {14-15},
abstract = {Using Computational Fluid Dynamics (CFD), new insights can be obtained into the working principles of Energy Saving Devices (ESDs), which all serve to increase the fuel efficiency of a ship. The advantages of using ReFRESCO to study ESDs are explored in this article.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Using Computational Fluid Dynamics (CFD), new insights can be obtained into the working principles of Energy Saving Devices (ESDs), which all serve to increase the fuel efficiency of a ship. The advantages of using ReFRESCO to study ESDs are explored in this article.
18.
Veldhuis, Christian; van der Ploeg, Auke
Improved hull optimisation using PARNASSOS Explorer Journal Article
In: MARIN Report, no. 109, pp. 20-21, 2013.
@article{Veldhuis2013,
title = {Improved hull optimisation using PARNASSOS Explorer},
author = {Christian Veldhuis and Auke van der Ploeg},
url = {http://www.marin.nl/extra/marin-bladermodules/html/109/#20},
year = {2013},
date = {2013-08-01},
journal = {MARIN Report},
number = {109},
pages = {20-21},
abstract = {MARIN’s inhouse RANS optimisation tool PARNASSOS Explorer is helping the industry discover more about the optimal hull form in order to improve performance and save energy.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
MARIN’s inhouse RANS optimisation tool PARNASSOS Explorer is helping the industry discover more about the optimal hull form in order to improve performance and save energy.
19.
Dang, Jie; Liu, Runwen; Pouw, Christiaan
Waterjet System Performance and Cavitation Test Procedures Conference
Proceedings of third International Symposium on Marine Propulsors (smp’13), Tasmania, Australia, SMP'13 2013.
@conference{Dang2013b,
title = {Waterjet System Performance and Cavitation Test Procedures},
author = {Jie Dang and Runwen Liu and Christiaan Pouw},
url = {http://www.marin.nl/web/Publications/Papers/Waterjet-System-Performance-and-Cavitation-Test-Procedures.htm
http://www.marinepropulsors.com/proceedings/2013/2B.1.pdf},
year = {2013},
date = {2013-05-05},
booktitle = {Proceedings of third International Symposium on Marine Propulsors (smp’13), Tasmania, Australia},
organization = {SMP'13},
abstract = {Different from marine propeller designs, which undergo standard stock and design propeller test programmes with detailed assessments of the final design (for the overall propulsive efficiency, the cavitation performance and the pressure fluctuations, etc.), waterjet systems of a final design are seldom tested for their system characteristics, the intake loss and the cavitation performance. It could be both due to economical reasons that waterjet system tests are relatively expensive. It could also be due to technical reasons, such as, that the operating point of a waterjet system does not vary too much for different operational conditions. This means that it performs also very well for all other operational (off-design) conditions once a waterjet system is well-designed for its design condition. However in practice, mismatching of power absorption and shaft rotational rate, and cavitation erosion, are now and then found after the sea trials of the waterjet propelled ships. Remedial action is needed then. In some cases, removing cavitation erosion can be rather difficult and simple modifications may not solve the problem.
In order to prevent those kinds of problems from the early design stage, waterjet system performance and cavitation tests of the final design are strongly recommended. Taking example of a Fast River Passenger Ferry, test procedures are discussed in detail in the present paper. The scale effects and the extrapolation method are also addressed. The results provide a good data set for CFD validation too. },
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Different from marine propeller designs, which undergo standard stock and design propeller test programmes with detailed assessments of the final design (for the overall propulsive efficiency, the cavitation performance and the pressure fluctuations, etc.), waterjet systems of a final design are seldom tested for their system characteristics, the intake loss and the cavitation performance. It could be both due to economical reasons that waterjet system tests are relatively expensive. It could also be due to technical reasons, such as, that the operating point of a waterjet system does not vary too much for different operational conditions. This means that it performs also very well for all other operational (off-design) conditions once a waterjet system is well-designed for its design condition. However in practice, mismatching of power absorption and shaft rotational rate, and cavitation erosion, are now and then found after the sea trials of the waterjet propelled ships. Remedial action is needed then. In some cases, removing cavitation erosion can be rather difficult and simple modifications may not solve the problem.
In order to prevent those kinds of problems from the early design stage, waterjet system performance and cavitation tests of the final design are strongly recommended. Taking example of a Fast River Passenger Ferry, test procedures are discussed in detail in the present paper. The scale effects and the extrapolation method are also addressed. The results provide a good data set for CFD validation too.
In order to prevent those kinds of problems from the early design stage, waterjet system performance and cavitation tests of the final design are strongly recommended. Taking example of a Fast River Passenger Ferry, test procedures are discussed in detail in the present paper. The scale effects and the extrapolation method are also addressed. The results provide a good data set for CFD validation too.
20.
Hooijmans, Patrick
Setting new standards in container ship design Journal Article
In: MARIN Report, no. 106, pp. 14, 2012.
@article{Hooijmans2012b,
title = {Setting new standards in container ship design},
author = {Patrick Hooijmans},
url = {http://www.marin.nl/web/Publications/Publication-items/Setting-new-standards-in-container-ship-design.htm},
year = {2012},
date = {2012-08-01},
journal = {MARIN Report},
number = {106},
pages = {14},
abstract = {Seaspan Saver, a 10,000 TEU container vessel is setting new standards in container ship design. MARIN is proud to have played a role in this pioneering design, which is highlighted here.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Seaspan Saver, a 10,000 TEU container vessel is setting new standards in container ship design. MARIN is proud to have played a role in this pioneering design, which is highlighted here.
2017
B. Vink, Schot; Toxopeus, S. L.
A Verification and Validation Study of CFD Simulations for the Flow Around A Tug Conference
20th Numerical Towing Tank Symposium (NuTTS), Wageningen, The Netherlands, 2017.
Abstract | Links | BibTeX | Tags: CFD, tugs, verification and validation
@conference{Vink2017,
title = {A Verification and Validation Study of CFD Simulations for the Flow Around A Tug},
author = {Vink, B., Schot, J., Vaz, G. and Toxopeus, S.L.},
url = {http://www.marin.nl/web/Publications/Publication-items/A-Verification-and-Validation-Study-of-CFD-Simulations-for-the-Flow-Around-A-Tug.htm},
year = {2017},
date = {2017-10-03},
booktitle = {20th Numerical Towing Tank Symposium (NuTTS), Wageningen, The Netherlands},
abstract = {An important vessel for the operational process in a harbour is the tug, a vessel built for the specific purpose of quickly manoeuvring larger vessels in waterways. The key features of a tug are the towing and escorting performances under optimal conditions, which are often reached when sailing under drift at high Froude numbers. Potential users or buyers are comparing tugs on these key features. Thus, for tug designers it is of significant importance to correctly predict the performance of new designs, therewith enabling themselves to verify possible improvements. These predictions, based on lift and drag characteristics of the hull and appendages, are frequently performed using free running or captive model tests, which can be expensive, give no thorough insight in flow specifics and although large-scale models are used still suffer from scale effects. An alternative approach is the use of viscous flow computations, also called Computational Fluid Dynamics (CFD).
This present work will initially estimate the experimental uncertainties from captive model tests to obtain correct validation material. Thereafter a verification and validation exercise of free surface simulations with the KSKL turbulence model and a drift angle of 15 deg will be presented. These are followed by a turbulence sensitivity study of the KSKL, SST, EARSM and DDES turbulence model and finally simulations at other drift angles with the KSKL turbulence will be presented.},
keywords = {CFD, tugs, verification and validation},
pubstate = {published},
tppubtype = {conference}
}
An important vessel for the operational process in a harbour is the tug, a vessel built for the specific purpose of quickly manoeuvring larger vessels in waterways. The key features of a tug are the towing and escorting performances under optimal conditions, which are often reached when sailing under drift at high Froude numbers. Potential users or buyers are comparing tugs on these key features. Thus, for tug designers it is of significant importance to correctly predict the performance of new designs, therewith enabling themselves to verify possible improvements. These predictions, based on lift and drag characteristics of the hull and appendages, are frequently performed using free running or captive model tests, which can be expensive, give no thorough insight in flow specifics and although large-scale models are used still suffer from scale effects. An alternative approach is the use of viscous flow computations, also called Computational Fluid Dynamics (CFD).
This present work will initially estimate the experimental uncertainties from captive model tests to obtain correct validation material. Thereafter a verification and validation exercise of free surface simulations with the KSKL turbulence model and a drift angle of 15 deg will be presented. These are followed by a turbulence sensitivity study of the KSKL, SST, EARSM and DDES turbulence model and finally simulations at other drift angles with the KSKL turbulence will be presented.
This present work will initially estimate the experimental uncertainties from captive model tests to obtain correct validation material. Thereafter a verification and validation exercise of free surface simulations with the KSKL turbulence model and a drift angle of 15 deg will be presented. These are followed by a turbulence sensitivity study of the KSKL, SST, EARSM and DDES turbulence model and finally simulations at other drift angles with the KSKL turbulence will be presented.
A. Maximiano, Vaz; Scharnke, J.
CFD Verification and Validation Study for a Captive Bullet Entry in Calm Water Conference
OMAE ASME 36th International Conference on Ocean, Offshore and Arctic Engineering, Trondheim, Norway, 2017.
Abstract | Links | BibTeX | Tags: CFD, ReFRESCO, verification and validation
@conference{Maximiano2017,
title = {CFD Verification and Validation Study for a Captive Bullet Entry in Calm Water},
author = {Maximiano, A., Vaz, G. and Scharnke, J.},
url = {http://www.marin.nl/web/Publications/Publication-items/CFD-Verification-and-Validation-Study-for-a-Captive-Bullet-Entry-in-Calm-Water.htm},
year = {2017},
date = {2017-06-25},
booktitle = {OMAE ASME 36th International Conference on Ocean, Offshore and Arctic Engineering, Trondheim, Norway},
pages = {OMAE2017-61666},
abstract = {As a step towards complex impact loads cases, e.g. lifeboat drop tests or ship/platform slamming in waves, a verification and validation (V&V) study is carried out with an open-usage community based CFD code ReFRESCO for a simple impact load test case: a captive axisymmetric generic lifeboat shape (bullet) that penetrates the water surface at a constant velocity and angle of attack. The quantities of interest are the body fixed longitudinal force FX, vertical force FZ, and pitch moment MYY.
The influence of the iterative convergence level, domain size and free surface modelling are investigated. Seven different grids and four time steps were used to assess the grid and time step sensitivity, in a total of 28 calculations. For the tested grids and time steps it was found that the results are more sensitive to the grid resolution than to the time step. The pressure distribution on the hull is correlated with the trends observed in the loads, and the relation between between relative and static pressure is found to be important for the calculated loads. An experimental test campaign was previously carried out by MARIN, and its results are used to validate the simulations performed. A very good match between experiments and simulations is found.
A V&V study is performed for the quantities of interest at nine different time instants covering the impact phase. The numerical uncertainties are obtained from a solution verification procedure [1]. The experimental uncertainties are estimated, and a validation exercise carried out according to the ASME standards [2]. The outcome of the validation exercise is an estimated 95% confidence interval for the modelling error, M. For FX the modelling error is below 15 N, for 8 out of 9 time instants. For FZ the modelling error is below 14 N, except at the time instants where, due to vibrations in the experimental setup, a larger value (up to 23 N) is found. For MYY the modelling error is under 5Nm. These results provide confidence in ReFRESCO for the simulation of free surface impact flows.},
keywords = {CFD, ReFRESCO, verification and validation},
pubstate = {published},
tppubtype = {conference}
}
As a step towards complex impact loads cases, e.g. lifeboat drop tests or ship/platform slamming in waves, a verification and validation (V&V) study is carried out with an open-usage community based CFD code ReFRESCO for a simple impact load test case: a captive axisymmetric generic lifeboat shape (bullet) that penetrates the water surface at a constant velocity and angle of attack. The quantities of interest are the body fixed longitudinal force FX, vertical force FZ, and pitch moment MYY.
The influence of the iterative convergence level, domain size and free surface modelling are investigated. Seven different grids and four time steps were used to assess the grid and time step sensitivity, in a total of 28 calculations. For the tested grids and time steps it was found that the results are more sensitive to the grid resolution than to the time step. The pressure distribution on the hull is correlated with the trends observed in the loads, and the relation between between relative and static pressure is found to be important for the calculated loads. An experimental test campaign was previously carried out by MARIN, and its results are used to validate the simulations performed. A very good match between experiments and simulations is found.
A V&V study is performed for the quantities of interest at nine different time instants covering the impact phase. The numerical uncertainties are obtained from a solution verification procedure [1]. The experimental uncertainties are estimated, and a validation exercise carried out according to the ASME standards [2]. The outcome of the validation exercise is an estimated 95% confidence interval for the modelling error, M. For FX the modelling error is below 15 N, for 8 out of 9 time instants. For FZ the modelling error is below 14 N, except at the time instants where, due to vibrations in the experimental setup, a larger value (up to 23 N) is found. For MYY the modelling error is under 5Nm. These results provide confidence in ReFRESCO for the simulation of free surface impact flows.
The influence of the iterative convergence level, domain size and free surface modelling are investigated. Seven different grids and four time steps were used to assess the grid and time step sensitivity, in a total of 28 calculations. For the tested grids and time steps it was found that the results are more sensitive to the grid resolution than to the time step. The pressure distribution on the hull is correlated with the trends observed in the loads, and the relation between between relative and static pressure is found to be important for the calculated loads. An experimental test campaign was previously carried out by MARIN, and its results are used to validate the simulations performed. A very good match between experiments and simulations is found.
A V&V study is performed for the quantities of interest at nine different time instants covering the impact phase. The numerical uncertainties are obtained from a solution verification procedure [1]. The experimental uncertainties are estimated, and a validation exercise carried out according to the ASME standards [2]. The outcome of the validation exercise is an estimated 95% confidence interval for the modelling error, M. For FX the modelling error is below 15 N, for 8 out of 9 time instants. For FZ the modelling error is below 14 N, except at the time instants where, due to vibrations in the experimental setup, a larger value (up to 23 N) is found. For MYY the modelling error is under 5Nm. These results provide confidence in ReFRESCO for the simulation of free surface impact flows.
A.H. Koop, Cozijn; Vaz, G.
Determining Thruster-Hull Interaction for a Drill-Ship Using CFD Conference
OMAE ASME 36th International Conference on Ocean, Offshore and Arctic Engineering, Trondheim, Norway, 2017.
Abstract | Links | BibTeX | Tags: CFD, thruster-hull interaction
@conference{Koop2017,
title = {Determining Thruster-Hull Interaction for a Drill-Ship Using CFD},
author = {Koop, A.H., Cozijn, H.C., Schrijvers, P. and Vaz, G.},
url = {http://www.marin.nl/web/Publications/Publication-items/Determining-ThrusterHull-Interaction-for-a-DrillShip-Using-CFD.htm},
year = {2017},
date = {2017-06-01},
booktitle = {OMAE ASME 36th International Conference on Ocean, Offshore and Arctic Engineering, Trondheim, Norway},
pages = {OMAE2017-61485},
abstract = {In this paper CFD results are presented for the thruster-hull interaction effects for a drillship with 6 azimuthing thrusters. The results using different approaches to model or simulate the propeller are compared and their advantages and disadvantages are discussed. The approaches investigated are the so-called Frozen Rotor approach, where the propeller rotation is modeled, the Actuator Disk approach with prescribed body forces and the unsteady Sliding Interface approach where the motion of the propeller is simulated in time.
First, open-water calculations for a tilted thruster are carried out using the Frozen Rotor approach. The open-water calculations are repeated using the Actuator Disk prescribing the propeller thrust and torque distribution obtained from the Frozen Rotor calculations. The results with Actuator Disk are very similar for the unit thrust and nozzle thrust compared to the results using the Frozen Rotor approach. Furthermore, the results using the Frozen Rotor or the Actuator Disk are very close to the experimental results for the nozzle thrust.
The thruster-hull interaction of one active thruster under the drillship is investigated using the Actuator Disk approach, the Frozen Rotor Approach and the Sliding Interface approach. A comparison to experimental results is presented for the thruster-hull interaction coefficients. Using the Actuator Disk a good agreement with the experiments is obtained. The results using the Actuator Disk and Sliding Interface are very similar to each other, but the computational costs for the Sliding Interface method are at least a factor 20 higher. The results using the Frozen Rotor deviate due to an unphysical wake behind the thruster.
Based on the results presented in this paper we conclude that, using the steady-state approach with the Actuator Disk, CFD can be a cost-efficient and accurate method to determine the thruster-hull interaction effects at bollard pull conditions for a typical offshore vessel.},
keywords = {CFD, thruster-hull interaction},
pubstate = {published},
tppubtype = {conference}
}
In this paper CFD results are presented for the thruster-hull interaction effects for a drillship with 6 azimuthing thrusters. The results using different approaches to model or simulate the propeller are compared and their advantages and disadvantages are discussed. The approaches investigated are the so-called Frozen Rotor approach, where the propeller rotation is modeled, the Actuator Disk approach with prescribed body forces and the unsteady Sliding Interface approach where the motion of the propeller is simulated in time.
First, open-water calculations for a tilted thruster are carried out using the Frozen Rotor approach. The open-water calculations are repeated using the Actuator Disk prescribing the propeller thrust and torque distribution obtained from the Frozen Rotor calculations. The results with Actuator Disk are very similar for the unit thrust and nozzle thrust compared to the results using the Frozen Rotor approach. Furthermore, the results using the Frozen Rotor or the Actuator Disk are very close to the experimental results for the nozzle thrust.
The thruster-hull interaction of one active thruster under the drillship is investigated using the Actuator Disk approach, the Frozen Rotor Approach and the Sliding Interface approach. A comparison to experimental results is presented for the thruster-hull interaction coefficients. Using the Actuator Disk a good agreement with the experiments is obtained. The results using the Actuator Disk and Sliding Interface are very similar to each other, but the computational costs for the Sliding Interface method are at least a factor 20 higher. The results using the Frozen Rotor deviate due to an unphysical wake behind the thruster.
Based on the results presented in this paper we conclude that, using the steady-state approach with the Actuator Disk, CFD can be a cost-efficient and accurate method to determine the thruster-hull interaction effects at bollard pull conditions for a typical offshore vessel.
First, open-water calculations for a tilted thruster are carried out using the Frozen Rotor approach. The open-water calculations are repeated using the Actuator Disk prescribing the propeller thrust and torque distribution obtained from the Frozen Rotor calculations. The results with Actuator Disk are very similar for the unit thrust and nozzle thrust compared to the results using the Frozen Rotor approach. Furthermore, the results using the Frozen Rotor or the Actuator Disk are very close to the experimental results for the nozzle thrust.
The thruster-hull interaction of one active thruster under the drillship is investigated using the Actuator Disk approach, the Frozen Rotor Approach and the Sliding Interface approach. A comparison to experimental results is presented for the thruster-hull interaction coefficients. Using the Actuator Disk a good agreement with the experiments is obtained. The results using the Actuator Disk and Sliding Interface are very similar to each other, but the computational costs for the Sliding Interface method are at least a factor 20 higher. The results using the Frozen Rotor deviate due to an unphysical wake behind the thruster.
Based on the results presented in this paper we conclude that, using the steady-state approach with the Actuator Disk, CFD can be a cost-efficient and accurate method to determine the thruster-hull interaction effects at bollard pull conditions for a typical offshore vessel.
A.R. Starke, Drakopoulos; Turnock, S. R.
VII International Conference on Computational Methods in Marine Engineering (MARINE2017), 2017.
Abstract | Links | BibTeX | Tags: CFD, full-scale validation, power prediction
@conference{Starke2017,
title = {RANS-based full-scale power predictions for a general cargo vessel, and comparison with sea-trial results},
author = {Starke, A.R., Drakopoulos, K., Toxopeus, S.L. and Turnock, S.R.},
url = {http://www.marin.nl/web/Publications/Publication-items/RANSbased-fullscale-power-predictions-for-a-general-cargo-vessel-and-comparison-with-seatrial-results.htm},
year = {2017},
date = {2017-05-01},
booktitle = {VII International Conference on Computational Methods in Marine Engineering (MARINE2017)},
abstract = {Blind self-propulsion predictions for the 2016 LR Workshop on Ship Scale Hydrodynamic Computer Simulation have been carried out to simulate the full scale performance of a self-propelled ship in ballast. The single screw ship of 11542 tonnes had been scanned in drydock so the computational model used the actual as operated hull form. It will be shown that using a hybrid RANS-BEM method, the predicted ship speeds at selfpropulsion are over-estimated by 0.17-0.28 knots compared to the trial data. The various aspects that influence the accuracy of the direct prediction of power and RPM using CFD are critically discussed.},
keywords = {CFD, full-scale validation, power prediction},
pubstate = {published},
tppubtype = {conference}
}
Blind self-propulsion predictions for the 2016 LR Workshop on Ship Scale Hydrodynamic Computer Simulation have been carried out to simulate the full scale performance of a self-propelled ship in ballast. The single screw ship of 11542 tonnes had been scanned in drydock so the computational model used the actual as operated hull form. It will be shown that using a hybrid RANS-BEM method, the predicted ship speeds at selfpropulsion are over-estimated by 0.17-0.28 knots compared to the trial data. The various aspects that influence the accuracy of the direct prediction of power and RPM using CFD are critically discussed.
Crepier, P.
Ship Resistance Prediction: Verification And Validation Exercise On Unstructured Grids Conference
VII International Conference on Computational Methods in Marine Engineering (MARINE2017), 2017.
Abstract | Links | BibTeX | Tags: CFD, Double-body, KVLCC2, Unstructured grid, Validation, verification
@conference{Crepier2017,
title = {Ship Resistance Prediction: Verification And Validation Exercise On Unstructured Grids},
author = {Crepier, P.},
url = {http://www.marin.nl/web/Publications/Publication-items/Ship-Resistance-Prediction-Verification-And-Validation-Exercise-On-Unstructured-Grids.htm},
year = {2017},
date = {2017-05-01},
booktitle = {VII International Conference on Computational Methods in Marine Engineering (MARINE2017)},
abstract = {The prediction of the resistance of a ship is, together with the propeller performance prediction, part of the key aspects during the design process of a ship, as it partly ensures the quality of the power-prediction. Body fitted structured grids for ship simulations can be rather challenging and time consuming to build, especially when dealing with appended ship geometries. For this reason, unstructured hexahedral trimmed grids are more and more used. Such grids can be build by various CFD package such as CD-Adapcos Star CCM+, NUMECAs Hexpress grid generator or OpenFOAMSs SnappyHexMesh. Although their use is increasing or even already adopted, the numerical uncertainty of these simulations seems to be a well-kept secret.
In the study presented, an attempt at quantifying the numerical uncertainty of the resistance for the combination of the RANS Solver ReFRESCO [1] with grids generated using the commercial package Hexpress is made. The studied case is the flow around the bare-hull KVLCC2 at model scale Reynolds number. Extensive verification and validation on the same test case has already been published for the combination of ReFRESCO and structured grids by Pereira et al. [2].
The method to generate grids as geometrically similar as possible is presented, and the uncertainty analysis by L. Ec¸a and M. Hoekstra [3] is performed on the integral results obtained.
The simulations are performed using the k − ω SST, k − ω TNT and the k −√kL turbulence models. The velocity fields calculated in the propeller plane are compared to the measured ones and to the results obtained by Pereira et al. [2] on structured grids.
The results show that the differences with the experimental results are in the same range as the differences obtained with structured grids. The numerical uncertainties are, however, higher. They are also strongly dependent on the turbulence model used, like for structured grids, and are spread between 1.3% and 12%.
Concerning the wake flow details, not all features present in the experimental results are obtained and, compared to structured grids, the flow features are smoothed. The wake flow is also influenced by the turbulence modelling and needs to be adressed in more detail.},
keywords = {CFD, Double-body, KVLCC2, Unstructured grid, Validation, verification},
pubstate = {published},
tppubtype = {conference}
}
The prediction of the resistance of a ship is, together with the propeller performance prediction, part of the key aspects during the design process of a ship, as it partly ensures the quality of the power-prediction. Body fitted structured grids for ship simulations can be rather challenging and time consuming to build, especially when dealing with appended ship geometries. For this reason, unstructured hexahedral trimmed grids are more and more used. Such grids can be build by various CFD package such as CD-Adapcos Star CCM+, NUMECAs Hexpress grid generator or OpenFOAMSs SnappyHexMesh. Although their use is increasing or even already adopted, the numerical uncertainty of these simulations seems to be a well-kept secret.
In the study presented, an attempt at quantifying the numerical uncertainty of the resistance for the combination of the RANS Solver ReFRESCO [1] with grids generated using the commercial package Hexpress is made. The studied case is the flow around the bare-hull KVLCC2 at model scale Reynolds number. Extensive verification and validation on the same test case has already been published for the combination of ReFRESCO and structured grids by Pereira et al. [2].
The method to generate grids as geometrically similar as possible is presented, and the uncertainty analysis by L. Ec¸a and M. Hoekstra [3] is performed on the integral results obtained.
The simulations are performed using the k − ω SST, k − ω TNT and the k −√kL turbulence models. The velocity fields calculated in the propeller plane are compared to the measured ones and to the results obtained by Pereira et al. [2] on structured grids.
The results show that the differences with the experimental results are in the same range as the differences obtained with structured grids. The numerical uncertainties are, however, higher. They are also strongly dependent on the turbulence model used, like for structured grids, and are spread between 1.3% and 12%.
Concerning the wake flow details, not all features present in the experimental results are obtained and, compared to structured grids, the flow features are smoothed. The wake flow is also influenced by the turbulence modelling and needs to be adressed in more detail.
In the study presented, an attempt at quantifying the numerical uncertainty of the resistance for the combination of the RANS Solver ReFRESCO [1] with grids generated using the commercial package Hexpress is made. The studied case is the flow around the bare-hull KVLCC2 at model scale Reynolds number. Extensive verification and validation on the same test case has already been published for the combination of ReFRESCO and structured grids by Pereira et al. [2].
The method to generate grids as geometrically similar as possible is presented, and the uncertainty analysis by L. Ec¸a and M. Hoekstra [3] is performed on the integral results obtained.
The simulations are performed using the k − ω SST, k − ω TNT and the k −√kL turbulence models. The velocity fields calculated in the propeller plane are compared to the measured ones and to the results obtained by Pereira et al. [2] on structured grids.
The results show that the differences with the experimental results are in the same range as the differences obtained with structured grids. The numerical uncertainties are, however, higher. They are also strongly dependent on the turbulence model used, like for structured grids, and are spread between 1.3% and 12%.
Concerning the wake flow details, not all features present in the experimental results are obtained and, compared to structured grids, the flow features are smoothed. The wake flow is also influenced by the turbulence modelling and needs to be adressed in more detail.
2016
Christian; Gornicz Veldhuis, Tomasz; Scholcz
13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark, no. ID080, Practical Design of Ships and Other Floating Structures 2016.
Abstract | Links | BibTeX | Tags: CFD, design of experiments, optimization, power, wake field
@conference{Veldhuis2016,
title = {Ship optimization using viscous flow computations in combination with generic shape variations and Design of Experiments},
author = {Veldhuis, Christian; Gornicz, Tomasz; Scholcz, Thomas},
url = {http://www.marin.nl/web/Publications/Papers/Ship-optimization-using-viscous-flow-computations-in-combination-with-generic-shape-variations-and-Design-of-Experiments.htm},
year = {2016},
date = {2016-09-04},
booktitle = {13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark},
journal = {Proceedings of PRADS2016 4th – 8th September, 2016 Copenhagen, Denmark},
number = {ID080},
organization = {Practical Design of Ships and Other Floating Structures},
abstract = {This paper discusses a procedure to optimize ship hull forms for minimum required power and best wake field quality, based on viscous flow computations. This research elaborates on an earlier optimization at MARIN (Van der Ploeg and Raven, 2010 and Van der Ploeg, Starke and Veldhuis, 2013). That optimization lead to a clear Pareto front and trends for a systematic variation study for the afterbody of a chemical tanker. In 2016, new steps are taken to ease and generalize the method of hull shape generation. In the previous study the design space was set up by means of ‘manually’ designed basis hull shapes. In the new approach we test the use of generic basis hull shapes which are automatically generated from one initial hull shape. If effective, this approach can speed up the design process significantly. Finally, we want to improve the process even further by using a Design of Exper-iments approach in which the systematic variations are re-placed by a more clever distribution of calculations over the design space. },
keywords = {CFD, design of experiments, optimization, power, wake field},
pubstate = {published},
tppubtype = {conference}
}
This paper discusses a procedure to optimize ship hull forms for minimum required power and best wake field quality, based on viscous flow computations. This research elaborates on an earlier optimization at MARIN (Van der Ploeg and Raven, 2010 and Van der Ploeg, Starke and Veldhuis, 2013). That optimization lead to a clear Pareto front and trends for a systematic variation study for the afterbody of a chemical tanker. In 2016, new steps are taken to ease and generalize the method of hull shape generation. In the previous study the design space was set up by means of ‘manually’ designed basis hull shapes. In the new approach we test the use of generic basis hull shapes which are automatically generated from one initial hull shape. If effective, this approach can speed up the design process significantly. Finally, we want to improve the process even further by using a Design of Exper-iments approach in which the systematic variations are re-placed by a more clever distribution of calculations over the design space.
Tomasz; van der Ploeg Gornics, Auke; Scholcz
Trim wedge optimization with viscous free surface computations Conference
Proceedings of PRADS2016, Copenhagen, Denmark, 2016.
Abstract | Links | BibTeX | Tags: CFD, free surface, optimization, scale effects, ship hydrodynamics, trim wedge
@conference{Gornics2016,
title = {Trim wedge optimization with viscous free surface computations},
author = {Gornics, Tomasz; van der Ploeg, Auke; Scholcz, Thomas},
url = {http://www.marin.nl/web/Publications/Papers/Trim-wedge-optimization-with-viscous-free-surface-computations.htm},
year = {2016},
date = {2016-09-04},
booktitle = {Proceedings of PRADS2016, Copenhagen, Denmark},
abstract = {A procedure for automatic optimization of a ship hull and
trim wedge is described, that is based on an evaluation
of a series of hull form/trim wedge combinations. These
evaluations are done with a RANS method that can accurately
and efficiently compute the viscous flow for several
transom flow regimes, ranging from completely dry
to (partly) wetted. The object function is an approximation
of the required power to maintain a given speed. Results
obtained from several trim wedge optimizations are
shown, computed and measured trends are compared and
computed scale effects in those trends are discussed. For
two examples, a considerable improvement of the object
function can be obtained. At full scale, the improvement
of the object function is stronger than at model scale.},
keywords = {CFD, free surface, optimization, scale effects, ship hydrodynamics, trim wedge},
pubstate = {published},
tppubtype = {conference}
}
A procedure for automatic optimization of a ship hull and
trim wedge is described, that is based on an evaluation
of a series of hull form/trim wedge combinations. These
evaluations are done with a RANS method that can accurately
and efficiently compute the viscous flow for several
transom flow regimes, ranging from completely dry
to (partly) wetted. The object function is an approximation
of the required power to maintain a given speed. Results
obtained from several trim wedge optimizations are
shown, computed and measured trends are compared and
computed scale effects in those trends are discussed. For
two examples, a considerable improvement of the object
function can be obtained. At full scale, the improvement
of the object function is stronger than at model scale.
trim wedge is described, that is based on an evaluation
of a series of hull form/trim wedge combinations. These
evaluations are done with a RANS method that can accurately
and efficiently compute the viscous flow for several
transom flow regimes, ranging from completely dry
to (partly) wetted. The object function is an approximation
of the required power to maintain a given speed. Results
obtained from several trim wedge optimizations are
shown, computed and measured trends are compared and
computed scale effects in those trends are discussed. For
two examples, a considerable improvement of the object
function can be obtained. At full scale, the improvement
of the object function is stronger than at model scale.
M. Kerkvliet, Carette; Straten, O. van
Analysis of free surface anti-roll tank using URANS. Verification and validation Conference
13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark, 2016.
Abstract | Links | BibTeX | Tags: anti-roll tank, ART, CFD, free surface, ReFRESCO, URANS, verification and validation
@conference{Kerkvliet2016,
title = {Analysis of free surface anti-roll tank using URANS. Verification and validation},
author = {Kerkvliet, M., Carette, N. and Straten, O. van},
url = {http://www.marin.nl/web/Publications/Papers/Analysis-of-free-surface-antiroll-tank-using-URANS.-Verification-and-validation-1.htm},
year = {2016},
date = {2016-09-04},
booktitle = {13th International Symposium on Practical Design of Ships (PRADS), Copenhagen, Denmark},
pages = {ID055},
abstract = {To prevent excessive roll motion of ships operating in seas, damping systems are often required. Exterior systems can be used like, bilge keels or active stabilizer fins, or interior systems like anti-roll tanks (ARTs). There are mainly two sorts of ARTs, i.e. free surface tanks and Utype tanks. Both types have been studied extensively in the past, e.g. by Watts (1883), Frahm (1911) and Verhagen and Wijngaarden (1965), but also more recently, e.g. by Lee and Vassalos (1996), Kerkvliet et al. (2014) and Carette (2015). The content of this paper is restricted to the free surface type ART, which is nowadays often used to increase the roll damping of ships passively. The main advantages of such an ART are the large damping moment at small roll amplitudes and the ease to adapt the response by changing the water level. The response of the tank is highly frequency and amplitude dependent with a strong non-linear character (Carette et al., 2016). Also the shape of the interior geometry, e.g. additional struts, plates or other flow obstructions, will have an effect on the response, which makes it difficult to predict the response by analytical models. Therefore, systematic oscillation tests are often performed by model-scale experiments or by use of Computational Fluid Dynamics (CFD). This paper shows the response of a two-dimensional (2D) and three-dimensional (3D) model-scale free surface ART using the CFD code ReFRESCO (www.refresco.org). The objective of this paper is to show which issues are important when CFD is used as a research and design tool. A verification and validation study is performed to determine numerical settings to obtain a good trade-off between accuracy and computational costs. The CFD results are validated against model-scale experimental results, based on the work of Carette (2015). The results show that CFD can be used as a simulation driven design tool to accurately predict the response of an ART.},
keywords = {anti-roll tank, ART, CFD, free surface, ReFRESCO, URANS, verification and validation},
pubstate = {published},
tppubtype = {conference}
}
To prevent excessive roll motion of ships operating in seas, damping systems are often required. Exterior systems can be used like, bilge keels or active stabilizer fins, or interior systems like anti-roll tanks (ARTs). There are mainly two sorts of ARTs, i.e. free surface tanks and Utype tanks. Both types have been studied extensively in the past, e.g. by Watts (1883), Frahm (1911) and Verhagen and Wijngaarden (1965), but also more recently, e.g. by Lee and Vassalos (1996), Kerkvliet et al. (2014) and Carette (2015). The content of this paper is restricted to the free surface type ART, which is nowadays often used to increase the roll damping of ships passively. The main advantages of such an ART are the large damping moment at small roll amplitudes and the ease to adapt the response by changing the water level. The response of the tank is highly frequency and amplitude dependent with a strong non-linear character (Carette et al., 2016). Also the shape of the interior geometry, e.g. additional struts, plates or other flow obstructions, will have an effect on the response, which makes it difficult to predict the response by analytical models. Therefore, systematic oscillation tests are often performed by model-scale experiments or by use of Computational Fluid Dynamics (CFD). This paper shows the response of a two-dimensional (2D) and three-dimensional (3D) model-scale free surface ART using the CFD code ReFRESCO (www.refresco.org). The objective of this paper is to show which issues are important when CFD is used as a research and design tool. A verification and validation study is performed to determine numerical settings to obtain a good trade-off between accuracy and computational costs. The CFD results are validated against model-scale experimental results, based on the work of Carette (2015). The results show that CFD can be used as a simulation driven design tool to accurately predict the response of an ART.
L. Eça, Vaz; Abreu, H.
Validation: What, Why And How Conference
OMAE ASME 35th International Conference on Ocean, Offshore and Arctic Engineering, Busan, South Korea, 2016.
Abstract | Links | BibTeX | Tags: a circular cylinder, a flat plate, CFD, EFD, KVLCC2, LNG carrier, Validation
@conference{Eça2016,
title = {Validation: What, Why And How},
author = {Eça, L., Vaz, G., Koop, A., Pereira, F. and Abreu, H.},
url = {http://www.marin.nl/web/Publications/Papers/Validation-What-Why-And-How.htm},
year = {2016},
date = {2016-06-19},
booktitle = {OMAE ASME 35th International Conference on Ocean, Offshore and Arctic Engineering, Busan, South Korea},
pages = {OMAE2016-54005},
abstract = {Offshore and Naval engineering have relied on physical models, i.e. experimental fluid dynamics (EFD), for several decades. Although the role of experiments in engineering is still unquestionable, some of the limitations of physical models, as for example domain size (blockage and scale effects), can be addressed using mathematical models, i.e. computational fluid dynamics (CFD). However, to gain confidence in the use of CFD it is fundamental to determine the modelling accuracy, i.e. to determine the difference between the “physical reality” and the selected mathematical model. The quantification of the modelling error is the goal of Validation. It must be emphasized that Validation applies to the mathematical model (and not the code) and is performed for selected flow quantities (the so-called quantities of interest).
Ideally, Validation would be performed comparing an exact measurement of the “physical reality” with the exact solution of the selected mathematical model. However, exact measurements do not exist and mathematical models for turbulent flows do not have analytical solutions. Therefore, procedures must be developed to take into account experimental and numerical uncertainties. Furthermore, the exact values of the flow parameters as for example Reynolds number, fluid viscosity or inlet turbulence quantities are often unknown, which leads to the so-called parameter uncertainty that also has to be dealt within the assessment of the modelling error.
The main goal of this paper is to demonstrate that the very popular designation of ”code X is validated” is meaningless without saying what is the mathematical model embedded in the code, what are the quantities of interest for the specific application and what is the Validation uncertainty imposed by the experimental, numerical and parameter uncertainties. Furthermore, we also illustrate that Validation is not a pass or fail exercise. A modelling error of 10% may be acceptable for a given application, whereas 1% may not be enough for a different one.
To this end, we present the application of the ASME V&V 20 Validation procedure for local set points and the metric for multiple set points to several practical test cases: prediction of transition from laminar to turbulent regime for the flow over a flat plate; flow around a circular cylinder; flow around the KVLCC2 tanker and current loads in shallow water for a LNG carrier. In most of these exercises, parameter uncertainty is assumed to be zero, which is an assumption often required for the so-called practical calculations due to the computational effort required to address it. Nonetheless, as an illustration of its application, the flow over the flat plate includes parameter uncertainty for the specification of the inlet turbulence quantities.},
keywords = {a circular cylinder, a flat plate, CFD, EFD, KVLCC2, LNG carrier, Validation},
pubstate = {published},
tppubtype = {conference}
}
Offshore and Naval engineering have relied on physical models, i.e. experimental fluid dynamics (EFD), for several decades. Although the role of experiments in engineering is still unquestionable, some of the limitations of physical models, as for example domain size (blockage and scale effects), can be addressed using mathematical models, i.e. computational fluid dynamics (CFD). However, to gain confidence in the use of CFD it is fundamental to determine the modelling accuracy, i.e. to determine the difference between the “physical reality” and the selected mathematical model. The quantification of the modelling error is the goal of Validation. It must be emphasized that Validation applies to the mathematical model (and not the code) and is performed for selected flow quantities (the so-called quantities of interest).
Ideally, Validation would be performed comparing an exact measurement of the “physical reality” with the exact solution of the selected mathematical model. However, exact measurements do not exist and mathematical models for turbulent flows do not have analytical solutions. Therefore, procedures must be developed to take into account experimental and numerical uncertainties. Furthermore, the exact values of the flow parameters as for example Reynolds number, fluid viscosity or inlet turbulence quantities are often unknown, which leads to the so-called parameter uncertainty that also has to be dealt within the assessment of the modelling error.
The main goal of this paper is to demonstrate that the very popular designation of ”code X is validated” is meaningless without saying what is the mathematical model embedded in the code, what are the quantities of interest for the specific application and what is the Validation uncertainty imposed by the experimental, numerical and parameter uncertainties. Furthermore, we also illustrate that Validation is not a pass or fail exercise. A modelling error of 10% may be acceptable for a given application, whereas 1% may not be enough for a different one.
To this end, we present the application of the ASME V&V 20 Validation procedure for local set points and the metric for multiple set points to several practical test cases: prediction of transition from laminar to turbulent regime for the flow over a flat plate; flow around a circular cylinder; flow around the KVLCC2 tanker and current loads in shallow water for a LNG carrier. In most of these exercises, parameter uncertainty is assumed to be zero, which is an assumption often required for the so-called practical calculations due to the computational effort required to address it. Nonetheless, as an illustration of its application, the flow over the flat plate includes parameter uncertainty for the specification of the inlet turbulence quantities.
Ideally, Validation would be performed comparing an exact measurement of the “physical reality” with the exact solution of the selected mathematical model. However, exact measurements do not exist and mathematical models for turbulent flows do not have analytical solutions. Therefore, procedures must be developed to take into account experimental and numerical uncertainties. Furthermore, the exact values of the flow parameters as for example Reynolds number, fluid viscosity or inlet turbulence quantities are often unknown, which leads to the so-called parameter uncertainty that also has to be dealt within the assessment of the modelling error.
The main goal of this paper is to demonstrate that the very popular designation of ”code X is validated” is meaningless without saying what is the mathematical model embedded in the code, what are the quantities of interest for the specific application and what is the Validation uncertainty imposed by the experimental, numerical and parameter uncertainties. Furthermore, we also illustrate that Validation is not a pass or fail exercise. A modelling error of 10% may be acceptable for a given application, whereas 1% may not be enough for a different one.
To this end, we present the application of the ASME V&V 20 Validation procedure for local set points and the metric for multiple set points to several practical test cases: prediction of transition from laminar to turbulent regime for the flow over a flat plate; flow around a circular cylinder; flow around the KVLCC2 tanker and current loads in shallow water for a LNG carrier. In most of these exercises, parameter uncertainty is assumed to be zero, which is an assumption often required for the so-called practical calculations due to the computational effort required to address it. Nonetheless, as an illustration of its application, the flow over the flat plate includes parameter uncertainty for the specification of the inlet turbulence quantities.
Toxopeus, S. L.; Bhawsinka, K.
Calculation of hydrodynamic interaction forces on a ship entering a Lock using CFD Conference
Fourth International Conference on Ship Manoeuvring in Shallow and Confined Water (MASHCON) - Ship Bottom Interaction, Hamburg, Germany, 2016.
Abstract | Links | BibTeX | Tags: bulk carrier, CFD, ReFRESCO, ROPES
@conference{Toxopeus2016,
title = {Calculation of hydrodynamic interaction forces on a ship entering a Lock using CFD},
author = {Toxopeus, S.L. and Bhawsinka, K.},
url = {http://www.marin.nl/web/Publications/Papers/Calculation-of-hydrodynamic-interaction-forces-on-a-ship-entering-a-Lock-using-CFD.htm},
doi = {10.18451/978-3-939230-38-0_34},
year = {2016},
date = {2016-05-01},
booktitle = {Fourth International Conference on Ship Manoeuvring in Shallow and Confined Water (MASHCON) - Ship Bottom Interaction, Hamburg, Germany},
pages = {6_01},
abstract = {Estimation of hydrodynamic interaction forces experienced by a ship entering a lock plays an important role in the initial design phase of the lock. These forces govern the speed at which a ship can enter the lock and also the tug requirement for facilitating such manoeuvres. Hence hydrodynamic interaction forces can influence the turnaround time and the operational cost of the locks. Traditionally these forces have been calculated using model tests or by potential flow solvers.
In this paper, a study is presented on predicting ship-lock interaction effects with the viscous-flow solver ReFRESCO. The scenario consists of a large-beam bulk carrier entering the Pierre Vandamme Lock in Zeebrugge, Belgium. To validate the predictions, existing model tests are used. Furthermore, the results are compared to potential flow computations and CFD results from literature to highlight the benefits of each approach.
The paper will show that with careful setup of the computations, reliable predictions of the ship-lock interaction effects can be obtained. In order to capture all physics of the interaction, viscous-flow computations are preferred above potential-flow predictions.},
keywords = {bulk carrier, CFD, ReFRESCO, ROPES},
pubstate = {published},
tppubtype = {conference}
}
Estimation of hydrodynamic interaction forces experienced by a ship entering a lock plays an important role in the initial design phase of the lock. These forces govern the speed at which a ship can enter the lock and also the tug requirement for facilitating such manoeuvres. Hence hydrodynamic interaction forces can influence the turnaround time and the operational cost of the locks. Traditionally these forces have been calculated using model tests or by potential flow solvers.
In this paper, a study is presented on predicting ship-lock interaction effects with the viscous-flow solver ReFRESCO. The scenario consists of a large-beam bulk carrier entering the Pierre Vandamme Lock in Zeebrugge, Belgium. To validate the predictions, existing model tests are used. Furthermore, the results are compared to potential flow computations and CFD results from literature to highlight the benefits of each approach.
The paper will show that with careful setup of the computations, reliable predictions of the ship-lock interaction effects can be obtained. In order to capture all physics of the interaction, viscous-flow computations are preferred above potential-flow predictions.
In this paper, a study is presented on predicting ship-lock interaction effects with the viscous-flow solver ReFRESCO. The scenario consists of a large-beam bulk carrier entering the Pierre Vandamme Lock in Zeebrugge, Belgium. To validate the predictions, existing model tests are used. Furthermore, the results are compared to potential flow computations and CFD results from literature to highlight the benefits of each approach.
The paper will show that with careful setup of the computations, reliable predictions of the ship-lock interaction effects can be obtained. In order to capture all physics of the interaction, viscous-flow computations are preferred above potential-flow predictions.
Henk; Flikkema Prins, Maarten; Schuiling
Green retrofitting through optimisation of hull-propulsion interaction - GRIP Conference
Proceedings of 6th Transport Research Arena, Warsaw, Poland, 2016.
Abstract | Links | BibTeX | Tags: CFD, Energy Saving Device, ESD, full scale validation, retrofitting, ship performance, structural
@conference{Prins2016,
title = {Green retrofitting through optimisation of hull-propulsion interaction - GRIP},
author = {Prins, Henk; Flikkema, Maarten; Schuiling, Bart; Xing-Kaeding, Y; Voermans, A. A. M.; Müller, M; Coache, S; Hasselaar, Thijs; Paboeuf, S},
url = {http://www.marin.nl/web/Publications/Papers/Green-retrofitting-through-optimisation-of-hullpropulsion-interaction-GRIP.htm },
year = {2016},
date = {2016-04-18},
booktitle = {Proceedings of 6th Transport Research Arena, Warsaw, Poland},
abstract = {In the FP7 project GRIP, partners have extensively studied Energy Saving Devices which improve the propulsive efficiency of ships. The research has focussed on an early assessment of the performance, yard processes for the installation of an ESD, structural issues related to ESDs, and the hydrodynamical working principles of ESDs. All the work came together in the final demonstration of the efficiency gain of an ESD on Uljanik built bulk carrier MV Valvoline.
To demonstrate the ESD design procedure and the potential performance gain of ESDs, a design competition was held between MARIN, HSVA and Vicus who designed a pre-duct, pre-swirl stator and rudder bulb respectively. Designs were evaluated based on the performance improvement, manufacturability and structural issues. The PSS designed by HSVA came out the best with a reduction of required propulsion power. CFD analysis has shown that the PSS creates a pre-swirl resulting in an increase of the propeller efficiency mainly affecting the upcoming blade trajectory. Speed trial procedures were evaluated by MARIN to come to a procedure to evaluate the performance change with a minimum uncertainty. Speed trials before and after installation of the PSS on the bulk carrier were performed in favourable environmental conditions resulting in a performance improvement of 6.8% at a speed of 16 knots.
This paper gives an overview of the work performed in the project by all partners resulting in the successful demonstration.},
keywords = {CFD, Energy Saving Device, ESD, full scale validation, retrofitting, ship performance, structural},
pubstate = {published},
tppubtype = {conference}
}
In the FP7 project GRIP, partners have extensively studied Energy Saving Devices which improve the propulsive efficiency of ships. The research has focussed on an early assessment of the performance, yard processes for the installation of an ESD, structural issues related to ESDs, and the hydrodynamical working principles of ESDs. All the work came together in the final demonstration of the efficiency gain of an ESD on Uljanik built bulk carrier MV Valvoline.
To demonstrate the ESD design procedure and the potential performance gain of ESDs, a design competition was held between MARIN, HSVA and Vicus who designed a pre-duct, pre-swirl stator and rudder bulb respectively. Designs were evaluated based on the performance improvement, manufacturability and structural issues. The PSS designed by HSVA came out the best with a reduction of required propulsion power. CFD analysis has shown that the PSS creates a pre-swirl resulting in an increase of the propeller efficiency mainly affecting the upcoming blade trajectory. Speed trial procedures were evaluated by MARIN to come to a procedure to evaluate the performance change with a minimum uncertainty. Speed trials before and after installation of the PSS on the bulk carrier were performed in favourable environmental conditions resulting in a performance improvement of 6.8% at a speed of 16 knots.
This paper gives an overview of the work performed in the project by all partners resulting in the successful demonstration.
To demonstrate the ESD design procedure and the potential performance gain of ESDs, a design competition was held between MARIN, HSVA and Vicus who designed a pre-duct, pre-swirl stator and rudder bulb respectively. Designs were evaluated based on the performance improvement, manufacturability and structural issues. The PSS designed by HSVA came out the best with a reduction of required propulsion power. CFD analysis has shown that the PSS creates a pre-swirl resulting in an increase of the propeller efficiency mainly affecting the upcoming blade trajectory. Speed trial procedures were evaluated by MARIN to come to a procedure to evaluate the performance change with a minimum uncertainty. Speed trials before and after installation of the PSS on the bulk carrier were performed in favourable environmental conditions resulting in a performance improvement of 6.8% at a speed of 16 knots.
This paper gives an overview of the work performed in the project by all partners resulting in the successful demonstration.
2015
Starke, Bram
A Workshop on CFD in Ship Hydrodynamics, Tokyo, Japan, no. 15-2, Tokyo 2015, 2015.
Abstract | Links | BibTeX | Tags: CFD, hybrid, PARNASSOS, PROCAL, RANS-BEM, self-propulsion, viscous
@conference{Starke2015,
title = {Viscous Free-Surface Power Predictions For Self-Propulsion Using A Hybrid RANS-BEM Coupling Procedure (PARNASSOS-PROCAL)},
author = {Bram Starke},
url = {http://www.marin.nl/web/Publications/Papers/Viscous-FreeSurface-Power-Predictions-For-SelfPropulsion-Using-A-Hybrid-RANSBEM-Coupling-Procedure-PARNASSOSPROCAL.htm},
year = {2015},
date = {2015-12-01},
booktitle = {A Workshop on CFD in Ship Hydrodynamics, Tokyo, Japan},
journal = {Tokyo 2015, A Workshop on CFD in Ship Hydrodynamics, Tokyo, Japan},
number = {15-2},
publisher = {Tokyo 2015},
abstract = {This paper presents results of computations for the 2015 CFD workshop in Tokyo. It briefly describes the RANS method used, the particular treatment of the free surface boundary conditions, and the coupling between the steady RANS code and a boundary element method used for the propeller analysis. Computations for the KCS (case 2.5) have been performed at five grids with different densities. It will be shown that mesh dependence of thrust, torque and RPM at the finest meshes is small, with comparison errors of approximately -0.3 per cent for the resistance, -1.8 per cent for RPM, +3.5 for KT and +5.9 per cent for KQ. The corresponding error estimation results in uncertainties of less than 1 per cent for the powering parameters, but this value may be too optimistic as a result on at least one more grid has to be generated to perform the uncertainty estimation correctly.},
keywords = {CFD, hybrid, PARNASSOS, PROCAL, RANS-BEM, self-propulsion, viscous},
pubstate = {published},
tppubtype = {conference}
}
This paper presents results of computations for the 2015 CFD workshop in Tokyo. It briefly describes the RANS method used, the particular treatment of the free surface boundary conditions, and the coupling between the steady RANS code and a boundary element method used for the propeller analysis. Computations for the KCS (case 2.5) have been performed at five grids with different densities. It will be shown that mesh dependence of thrust, torque and RPM at the finest meshes is small, with comparison errors of approximately -0.3 per cent for the resistance, -1.8 per cent for RPM, +3.5 for KT and +5.9 per cent for KQ. The corresponding error estimation results in uncertainties of less than 1 per cent for the powering parameters, but this value may be too optimistic as a result on at least one more grid has to be generated to perform the uncertainty estimation correctly.
Prins, Henk
MARIN invests in the future as CFD takes on more prominent role Journal Article
In: MARIN Report, no. 115, pp. 12-13, 2015.
Abstract | Links | BibTeX | Tags: CFD, computer cluster, ReFRESCO
@article{Prins2015,
title = {MARIN invests in the future as CFD takes on more prominent role},
author = {Henk Prins},
url = {http://content.yudu.com/web/1r3p1/0A3a046/MR115/html/index.html?page=12},
year = {2015},
date = {2015-08-01},
journal = {MARIN Report},
number = {115},
pages = {12-13},
abstract = {To facilitate the use of reliable CFD in the design and engineering process, MARIN has invested in a new, large computer cluster, and is sharing its CFD code ReFRESCO with its customers.},
keywords = {CFD, computer cluster, ReFRESCO},
pubstate = {published},
tppubtype = {article}
}
To facilitate the use of reliable CFD in the design and engineering process, MARIN has invested in a new, large computer cluster, and is sharing its CFD code ReFRESCO with its customers.
Dang, Jie; Chen, Hao; Rueda, Luis; Willemsen, Harry
Fourth International Symposium on Marine Propulsors (SMP), Austin, Texas , Symposiums on Marine Propulsors 2015.
Abstract | Links | BibTeX | Tags: aframax, asymmetric aftbody, CFD, efficiency, Energy Saving Device, ESD, propeller, RANS-BEM, tanker
@conference{Dang2015,
title = {Integrated Design of Asymmetric Aftbody and Propeller for an Aframax Tanker to Maximize Energy Efficiency},
author = {Jie Dang and Hao Chen and Luis Rueda and Harry Willemsen},
url = {http://www.marin.nl/web/Publications/Papers/Integrated-Design-of-Asymmetric-Aftbody-and-Propeller-for-an-Aframax-Tanker-to-Maximize-Energy-Efficiency.htm
http://www.marinepropulsors.com/proceedings.php},
year = {2015},
date = {2015-06-01},
booktitle = {Fourth International Symposium on Marine Propulsors (SMP), Austin, Texas },
organization = {Symposiums on Marine Propulsors},
abstract = {With the implementation of the EEDI, energy saving and emission reduction of ships, especially merchant ships, become more and more important. To achieve high efficiency and low emissions, recently Energy Saving Devices (ESDs) have been re-studied and installed to many ships, both new buildings and also retrofits. Various ESDs, including new concepts, have been tested in model scale and large improvements on energy efficiency have been confirmed. However due to the fact that most ESDs are fitted in the wake field, the performance of the ESDs is influenced by scale effects. For the operators, the fouling and the structure integration of the ESD’s with the hull are the important issues to make decisions on applying ESDs to their ships.
Distinguished from the ESDs where extra ‘appendages’ have to be added in front of and/or behind a propeller, an asymmetric aftbody can also change the flow towards the propeller without appendages. The wake with pre-swirl generated by an asymmetric aftbody is in general more uniform than that by an ESD (such as a pre-stator with finite blades) and with almost no penalty on the ship’s resistance. By integrating a propeller, a ship with asymmetric aftbody can be designed so that the hull-propeller interaction is optimized for its total propulsive efficiency and the required shaft power is minimized at given speed.
In this paper, discussions have been given on the optimization procedure by using the Computational Fluid Dynamics (CFD) towards a fully-integrated hull-propeller design to maximize the energy efficiency of a single screw ship. Comparative model tests, carried out with optimized symmetric and asymmetric ships, showed more than 6% gain in efficiency with a moderate asymmetric aftbody, without detriments to its course stability. },
keywords = {aframax, asymmetric aftbody, CFD, efficiency, Energy Saving Device, ESD, propeller, RANS-BEM, tanker},
pubstate = {published},
tppubtype = {conference}
}
With the implementation of the EEDI, energy saving and emission reduction of ships, especially merchant ships, become more and more important. To achieve high efficiency and low emissions, recently Energy Saving Devices (ESDs) have been re-studied and installed to many ships, both new buildings and also retrofits. Various ESDs, including new concepts, have been tested in model scale and large improvements on energy efficiency have been confirmed. However due to the fact that most ESDs are fitted in the wake field, the performance of the ESDs is influenced by scale effects. For the operators, the fouling and the structure integration of the ESD’s with the hull are the important issues to make decisions on applying ESDs to their ships.
Distinguished from the ESDs where extra ‘appendages’ have to be added in front of and/or behind a propeller, an asymmetric aftbody can also change the flow towards the propeller without appendages. The wake with pre-swirl generated by an asymmetric aftbody is in general more uniform than that by an ESD (such as a pre-stator with finite blades) and with almost no penalty on the ship’s resistance. By integrating a propeller, a ship with asymmetric aftbody can be designed so that the hull-propeller interaction is optimized for its total propulsive efficiency and the required shaft power is minimized at given speed.
In this paper, discussions have been given on the optimization procedure by using the Computational Fluid Dynamics (CFD) towards a fully-integrated hull-propeller design to maximize the energy efficiency of a single screw ship. Comparative model tests, carried out with optimized symmetric and asymmetric ships, showed more than 6% gain in efficiency with a moderate asymmetric aftbody, without detriments to its course stability.
Distinguished from the ESDs where extra ‘appendages’ have to be added in front of and/or behind a propeller, an asymmetric aftbody can also change the flow towards the propeller without appendages. The wake with pre-swirl generated by an asymmetric aftbody is in general more uniform than that by an ESD (such as a pre-stator with finite blades) and with almost no penalty on the ship’s resistance. By integrating a propeller, a ship with asymmetric aftbody can be designed so that the hull-propeller interaction is optimized for its total propulsive efficiency and the required shaft power is minimized at given speed.
In this paper, discussions have been given on the optimization procedure by using the Computational Fluid Dynamics (CFD) towards a fully-integrated hull-propeller design to maximize the energy efficiency of a single screw ship. Comparative model tests, carried out with optimized symmetric and asymmetric ships, showed more than 6% gain in efficiency with a moderate asymmetric aftbody, without detriments to its course stability.
2014
van der Meij, Karola; Raven, Hoyte
Promising hydrodynamic improvements for inland vessels Conference
EIWN Conference, Budapest, Hungary, European Inland Waterway Navigation Conference , 2014.
Abstract | Links | BibTeX | Tags: CFD, efficiency, inland ship design, shallow water
@conference{Meij2014,
title = {Promising hydrodynamic improvements for inland vessels},
author = {Karola van der Meij and Hoyte Raven},
url = {http://www.marin.nl/web/Publications/Publication-items/Promising-Hydrodynamic-Improvements-for-Inland-Vessels-1.htm
},
year = {2014},
date = {2014-09-10},
booktitle = {EIWN Conference, Budapest, Hungary},
publisher = {European Inland Waterway Navigation Conference },
abstract = {In the EU project Move IT! and the Joint Industry Project SAVE, extensive CFD calculations have been performed for several existing inland vessels. The objective was to investigate possible retrofit options to improve the hydrodynamic performance, and to determine the potential reduction in fuel consumption. This paper presents the results of the CFD calculations performed for the vessels. Different bow shapes have been analysed and a detailed investigation was performed on the shape of the aftship, especially focussing on the tunnel design. Some of the improvements were very promising and provide an interesting basis for inland ship design in general.
},
keywords = {CFD, efficiency, inland ship design, shallow water},
pubstate = {published},
tppubtype = {conference}
}
In the EU project Move IT! and the Joint Industry Project SAVE, extensive CFD calculations have been performed for several existing inland vessels. The objective was to investigate possible retrofit options to improve the hydrodynamic performance, and to determine the potential reduction in fuel consumption. This paper presents the results of the CFD calculations performed for the vessels. Different bow shapes have been analysed and a detailed investigation was performed on the shape of the aftship, especially focussing on the tunnel design. Some of the improvements were very promising and provide an interesting basis for inland ship design in general.
2013
van der Ploeg, Auke; Starke, Bram; Veldhuis, Christian
Optimization of a Chemical Tanker with Free-surface Viscous Flow Computations Conference
Proceedings of the PRADS2013, CECO, Changwon City, Korea, no. 096, Practical Design of Ships and Other Floating Structures 2013.
Abstract | Links | BibTeX | Tags: CFD, Fuel consumption, ship design, tanker
@conference{Ploeg2013,
title = {Optimization of a Chemical Tanker with Free-surface Viscous Flow Computations},
author = {Auke van der Ploeg and Bram Starke and Christian Veldhuis},
url = {http://www.marin.nl/web/Publications/Papers/Optimization-of-a-Chemical-Tanker-with-Freesurface-Viscous-Flow-Computations.htm},
year = {2013},
date = {2013-10-01},
booktitle = {Proceedings of the PRADS2013, CECO, Changwon City, Korea},
journal = {Proceedigs of the PRADS 2013},
number = {096},
organization = {Practical Design of Ships and Other Floating Structures},
abstract = {This paper discusses a procedure to optimize ship hull forms for minimum required power and best wake field quality, based on CFD computations of the viscous flow. A flexible and effective definition of parametric hull form variations is used, based on interpolation between basis hull forms. All RANS computations were performed for full-scale Reynolds number. An initial optimization has been obtained neglecting the ship’s wave making. Clear Pareto fronts and trends in the solutions are obtained in a systematic variation study for the afterbody of a chemical tanker. In addition we performed a systematic variation using RANS free surface, to study the influence of wave making on the computed trends. As a result, a further decrease in the object functions could be obtained and another hull form appeared to be optimal.},
keywords = {CFD, Fuel consumption, ship design, tanker},
pubstate = {published},
tppubtype = {conference}
}
This paper discusses a procedure to optimize ship hull forms for minimum required power and best wake field quality, based on CFD computations of the viscous flow. A flexible and effective definition of parametric hull form variations is used, based on interpolation between basis hull forms. All RANS computations were performed for full-scale Reynolds number. An initial optimization has been obtained neglecting the ship’s wave making. Clear Pareto fronts and trends in the solutions are obtained in a systematic variation study for the afterbody of a chemical tanker. In addition we performed a systematic variation using RANS free surface, to study the influence of wave making on the computed trends. As a result, a further decrease in the object functions could be obtained and another hull form appeared to be optimal.
Schuiling, Bart; vaz, Guilherme
ReFRESCO plays major role in understanding and designing Energy Saving Devices Journal Article
In: MARIN Report, no. 109, pp. 14-15, 2013.
Abstract | Links | BibTeX | Tags: CFD, Energy Saving Device, ESD, ReFRESCO
@article{Schuiling2013,
title = {ReFRESCO plays major role in understanding and designing Energy Saving Devices},
author = {Bart Schuiling and Guilherme vaz},
url = {http://www.marin.nl/extra/marin-bladermodules/html/109/#14},
year = {2013},
date = {2013-08-01},
journal = {MARIN Report},
number = {109},
pages = {14-15},
abstract = {Using Computational Fluid Dynamics (CFD), new insights can be obtained into the working principles of Energy Saving Devices (ESDs), which all serve to increase the fuel efficiency of a ship. The advantages of using ReFRESCO to study ESDs are explored in this article.},
keywords = {CFD, Energy Saving Device, ESD, ReFRESCO},
pubstate = {published},
tppubtype = {article}
}
Using Computational Fluid Dynamics (CFD), new insights can be obtained into the working principles of Energy Saving Devices (ESDs), which all serve to increase the fuel efficiency of a ship. The advantages of using ReFRESCO to study ESDs are explored in this article.
Veldhuis, Christian; van der Ploeg, Auke
Improved hull optimisation using PARNASSOS Explorer Journal Article
In: MARIN Report, no. 109, pp. 20-21, 2013.
Abstract | Links | BibTeX | Tags: CFD, Explorer, improve performance, PARNASSOS, RANS, save engergy
@article{Veldhuis2013,
title = {Improved hull optimisation using PARNASSOS Explorer},
author = {Christian Veldhuis and Auke van der Ploeg},
url = {http://www.marin.nl/extra/marin-bladermodules/html/109/#20},
year = {2013},
date = {2013-08-01},
journal = {MARIN Report},
number = {109},
pages = {20-21},
abstract = {MARIN’s inhouse RANS optimisation tool PARNASSOS Explorer is helping the industry discover more about the optimal hull form in order to improve performance and save energy.},
keywords = {CFD, Explorer, improve performance, PARNASSOS, RANS, save engergy},
pubstate = {published},
tppubtype = {article}
}
MARIN’s inhouse RANS optimisation tool PARNASSOS Explorer is helping the industry discover more about the optimal hull form in order to improve performance and save energy.
Dang, Jie; Liu, Runwen; Pouw, Christiaan
Waterjet System Performance and Cavitation Test Procedures Conference
Proceedings of third International Symposium on Marine Propulsors (smp’13), Tasmania, Australia, SMP'13 2013.
Abstract | Links | BibTeX | Tags: cavitation, CFD, procedures, waterjet
@conference{Dang2013b,
title = {Waterjet System Performance and Cavitation Test Procedures},
author = {Jie Dang and Runwen Liu and Christiaan Pouw},
url = {http://www.marin.nl/web/Publications/Papers/Waterjet-System-Performance-and-Cavitation-Test-Procedures.htm
http://www.marinepropulsors.com/proceedings/2013/2B.1.pdf},
year = {2013},
date = {2013-05-05},
booktitle = {Proceedings of third International Symposium on Marine Propulsors (smp’13), Tasmania, Australia},
organization = {SMP'13},
abstract = {Different from marine propeller designs, which undergo standard stock and design propeller test programmes with detailed assessments of the final design (for the overall propulsive efficiency, the cavitation performance and the pressure fluctuations, etc.), waterjet systems of a final design are seldom tested for their system characteristics, the intake loss and the cavitation performance. It could be both due to economical reasons that waterjet system tests are relatively expensive. It could also be due to technical reasons, such as, that the operating point of a waterjet system does not vary too much for different operational conditions. This means that it performs also very well for all other operational (off-design) conditions once a waterjet system is well-designed for its design condition. However in practice, mismatching of power absorption and shaft rotational rate, and cavitation erosion, are now and then found after the sea trials of the waterjet propelled ships. Remedial action is needed then. In some cases, removing cavitation erosion can be rather difficult and simple modifications may not solve the problem.
In order to prevent those kinds of problems from the early design stage, waterjet system performance and cavitation tests of the final design are strongly recommended. Taking example of a Fast River Passenger Ferry, test procedures are discussed in detail in the present paper. The scale effects and the extrapolation method are also addressed. The results provide a good data set for CFD validation too. },
keywords = {cavitation, CFD, procedures, waterjet},
pubstate = {published},
tppubtype = {conference}
}
Different from marine propeller designs, which undergo standard stock and design propeller test programmes with detailed assessments of the final design (for the overall propulsive efficiency, the cavitation performance and the pressure fluctuations, etc.), waterjet systems of a final design are seldom tested for their system characteristics, the intake loss and the cavitation performance. It could be both due to economical reasons that waterjet system tests are relatively expensive. It could also be due to technical reasons, such as, that the operating point of a waterjet system does not vary too much for different operational conditions. This means that it performs also very well for all other operational (off-design) conditions once a waterjet system is well-designed for its design condition. However in practice, mismatching of power absorption and shaft rotational rate, and cavitation erosion, are now and then found after the sea trials of the waterjet propelled ships. Remedial action is needed then. In some cases, removing cavitation erosion can be rather difficult and simple modifications may not solve the problem.
In order to prevent those kinds of problems from the early design stage, waterjet system performance and cavitation tests of the final design are strongly recommended. Taking example of a Fast River Passenger Ferry, test procedures are discussed in detail in the present paper. The scale effects and the extrapolation method are also addressed. The results provide a good data set for CFD validation too.
In order to prevent those kinds of problems from the early design stage, waterjet system performance and cavitation tests of the final design are strongly recommended. Taking example of a Fast River Passenger Ferry, test procedures are discussed in detail in the present paper. The scale effects and the extrapolation method are also addressed. The results provide a good data set for CFD validation too.
2012
Hooijmans, Patrick
Setting new standards in container ship design Journal Article
In: MARIN Report, no. 106, pp. 14, 2012.
Abstract | Links | BibTeX | Tags: 20000TEU, cavitation, CFD, containerships
@article{Hooijmans2012b,
title = {Setting new standards in container ship design},
author = {Patrick Hooijmans},
url = {http://www.marin.nl/web/Publications/Publication-items/Setting-new-standards-in-container-ship-design.htm},
year = {2012},
date = {2012-08-01},
journal = {MARIN Report},
number = {106},
pages = {14},
abstract = {Seaspan Saver, a 10,000 TEU container vessel is setting new standards in container ship design. MARIN is proud to have played a role in this pioneering design, which is highlighted here.},
keywords = {20000TEU, cavitation, CFD, containerships},
pubstate = {published},
tppubtype = {article}
}
Seaspan Saver, a 10,000 TEU container vessel is setting new standards in container ship design. MARIN is proud to have played a role in this pioneering design, which is highlighted here.
Dang, Jie
Proceedings of the 31st International Conference on Ocean, Offshore and Arctic Engineering, Rio de Janeiro, Brazil , no. OMAE2012-83053 , ASME - OMAE2012 2012.
Abstract | Links | BibTeX | Tags: CFD, ESD, Fuel consumption
@conference{Dang2012b,
title = {An Exploratory Study on the Working Principles of Energy Saving Devices (ESDS) - PIV, CFD Investigations and ESD Design Guidelines},
author = {Jie Dang},
url = {http://www.marin.nl/web/Publications/Papers/An-Exploratory-Study-on-the-Working-Principles-of-Energy-Saving-Devices-ESDS-PIV-CFD-Investigations-and-ESD-Design-Guidelines-1.htm},
year = {2012},
date = {2012-06-01},
booktitle = {Proceedings of the 31st International Conference on Ocean, Offshore and Arctic Engineering, Rio de Janeiro, Brazil },
number = {OMAE2012-83053 },
organization = {ASME - OMAE2012},
abstract = {The Maritime Research Institute Netherlands (MARIN) has recently started a Joint Industry Project (JIP) called ESD-JILI, investigating the working principles of energy saving devices (ESDs). Within the framework of this JIP, three ESDs have been selected and thoroughly investigated. They are a Pre-Duct with an inner Stator (PDS), a Pre-Swirl Stator (PSS) with asymmetric blade design and Hub Fins (HFs). The investigations have been carried out by using dedicated force and moment sensors to measure all the components of the ESDs independently during the propulsion tests, by using Particle Image Velocimetry (PIV) to measure the flow before, in-plane and behind the propeller and the ESDs, and by using Smart Ship Model technology (Wijngaarden 2011) to simulate the full-scale wake field during the model tests to gain insights on scale effects of the ESDs. At the same time, computational fluid dynamics (CFD) calculations are also carried out in order to further deepen the understanding of the working principles of the selected ESDs, and to assist the ESDs designs under certain guidelines. Some of the results of the study have been published to the Greenship’2011 Conference (Dang et al 2011). The flow details around the propulsion system with the PDS, which were obtained by both PIV measurements and CFD calculations, and the energy balance of the ship-propulsion system with a PDS are further investigated and reported here. Based on the results of the studies, the principle guidelines for ESD designs for single screw merchant ships have been proposed. },
keywords = {CFD, ESD, Fuel consumption},
pubstate = {published},
tppubtype = {conference}
}
The Maritime Research Institute Netherlands (MARIN) has recently started a Joint Industry Project (JIP) called ESD-JILI, investigating the working principles of energy saving devices (ESDs). Within the framework of this JIP, three ESDs have been selected and thoroughly investigated. They are a Pre-Duct with an inner Stator (PDS), a Pre-Swirl Stator (PSS) with asymmetric blade design and Hub Fins (HFs). The investigations have been carried out by using dedicated force and moment sensors to measure all the components of the ESDs independently during the propulsion tests, by using Particle Image Velocimetry (PIV) to measure the flow before, in-plane and behind the propeller and the ESDs, and by using Smart Ship Model technology (Wijngaarden 2011) to simulate the full-scale wake field during the model tests to gain insights on scale effects of the ESDs. At the same time, computational fluid dynamics (CFD) calculations are also carried out in order to further deepen the understanding of the working principles of the selected ESDs, and to assist the ESDs designs under certain guidelines. Some of the results of the study have been published to the Greenship’2011 Conference (Dang et al 2011). The flow details around the propulsion system with the PDS, which were obtained by both PIV measurements and CFD calculations, and the energy balance of the ship-propulsion system with a PDS are further investigated and reported here. Based on the results of the studies, the principle guidelines for ESD designs for single screw merchant ships have been proposed.
2011
Dallinga, Reint
Prediction of added resistance of ships in waves under further scrutiny Journal Article
In: MARIN Report, no. 104, pp. 12-13, 2011.
Abstract | Links | BibTeX | Tags: added resistance in waves, CFD, motions, seakeeping
@article{Dallinga2011,
title = {Prediction of added resistance of ships in waves under further scrutiny},
author = {Reint Dallinga},
url = {http://www.marin.nl/web/Publications/Publication-items/Prediction-of-added-resistance-of-ships-in-waves-under-further-scrutiny.htm},
year = {2011},
date = {2011-12-01},
journal = {MARIN Report},
number = {104},
pages = {12-13},
institution = {MARIN },
abstract = {MARIN investigates the merits of a Rankine source method in the prediction of added resistance.},
keywords = {added resistance in waves, CFD, motions, seakeeping},
pubstate = {published},
tppubtype = {article}
}
MARIN investigates the merits of a Rankine source method in the prediction of added resistance.
Zondervan, Gert-Jan; Dang, Jie
MARIN spearheads propulsion improvements Journal Article
In: MARIN Report, no. 104, pp. 16-17, 2011.
Abstract | Links | BibTeX | Tags: CFD, efficiency, ESD, Fuel consumption, propeller
@article{zondervan2011,
title = {MARIN spearheads propulsion improvements},
author = {Gert-Jan Zondervan and Jie Dang},
url = {http://www.marin.nl/web/Publications/Publication-items/MARIN-spearheads-propulsion-improvements.htm},
year = {2011},
date = {2011-12-01},
journal = {MARIN Report},
number = {104},
pages = {16-17},
abstract = {Fuel saving and emission reduction are motivating factors in the drive to improve marine propulsor technology and in the renewed interest in special devices that improve propulsion. Together with the industry, MARIN is actively investigating their working principles and the critical design aspects, using modern design and analysis tools.},
keywords = {CFD, efficiency, ESD, Fuel consumption, propeller},
pubstate = {published},
tppubtype = {article}
}
Fuel saving and emission reduction are motivating factors in the drive to improve marine propulsor technology and in the renewed interest in special devices that improve propulsion. Together with the industry, MARIN is actively investigating their working principles and the critical design aspects, using modern design and analysis tools.
Dang, Jie; Chen, Hao; Dong, Guoxiang; van der Ploeg, Auke; Hallmann, Rink; Mauro, Francesco
An Exploratory Study on the Working Principles of Energy Saving Devices (ESDs) Conference
Symposium on Green Ship Technology, Wuxi, China, October 201, Greenship'2011 2011.
Abstract | Links | BibTeX | Tags: CFD, duct, efficiency, Energy Saving Device, ESD, ESD-JILI, PBCF, PIV, stator
@conference{Dang2011,
title = {An Exploratory Study on the Working Principles of Energy Saving Devices (ESDs)},
author = {Jie Dang and Hao Chen and Guoxiang Dong and Auke van der Ploeg and Rink Hallmann and Francesco Mauro},
url = {http://www.marin.nl/web/News/News-items/An-Exploratory-Study-on-the-Working-Principles-of-Energy-Saving-Devices-ESDs.htm},
year = {2011},
date = {2011-10-01},
booktitle = {Symposium on Green Ship Technology, Wuxi, China, October 201},
organization = {Greenship'2011},
abstract = { new Joint Industry Project (JIP) has been initiated recently by MARIN, called ESD-JILI (机理), looking into the working principles and scale effects on Energy Saving Devices (ESDs).
Three ESDs have been chosen for the investigations in the first phase. They were a preduct with a supporting stator in the duct, a pre-swirl stator with asymmetric blade design and Propeller Boss Cap Fins (PBCF). Measurements of forces and moments on all components of the ESDs have been carried out in selfpropulsion model tests with dedicated sensors. Particle Image Velocimetry (PIV) technique has been used in the investigation of the detailed flow around the ESDs. In order to investigate the scale effects in model tests, a fullscale wake field was approximated by a ‘smart ship model’. Computational Fluid Dynamics (CFD) calculations were carried out both for designing the smart ship model and also for the detailed flow around the ESDs. Some findings and fundamental issues on scale-effects of the ESDs are addressed in this paper. },
keywords = {CFD, duct, efficiency, Energy Saving Device, ESD, ESD-JILI, PBCF, PIV, stator},
pubstate = {published},
tppubtype = {conference}
}
new Joint Industry Project (JIP) has been initiated recently by MARIN, called ESD-JILI (机理), looking into the working principles and scale effects on Energy Saving Devices (ESDs).
Three ESDs have been chosen for the investigations in the first phase. They were a preduct with a supporting stator in the duct, a pre-swirl stator with asymmetric blade design and Propeller Boss Cap Fins (PBCF). Measurements of forces and moments on all components of the ESDs have been carried out in selfpropulsion model tests with dedicated sensors. Particle Image Velocimetry (PIV) technique has been used in the investigation of the detailed flow around the ESDs. In order to investigate the scale effects in model tests, a fullscale wake field was approximated by a ‘smart ship model’. Computational Fluid Dynamics (CFD) calculations were carried out both for designing the smart ship model and also for the detailed flow around the ESDs. Some findings and fundamental issues on scale-effects of the ESDs are addressed in this paper.
Three ESDs have been chosen for the investigations in the first phase. They were a preduct with a supporting stator in the duct, a pre-swirl stator with asymmetric blade design and Propeller Boss Cap Fins (PBCF). Measurements of forces and moments on all components of the ESDs have been carried out in selfpropulsion model tests with dedicated sensors. Particle Image Velocimetry (PIV) technique has been used in the investigation of the detailed flow around the ESDs. In order to investigate the scale effects in model tests, a fullscale wake field was approximated by a ‘smart ship model’. Computational Fluid Dynamics (CFD) calculations were carried out both for designing the smart ship model and also for the detailed flow around the ESDs. Some findings and fundamental issues on scale-effects of the ESDs are addressed in this paper.