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新JIP:海上间歇无人值守驾驶台
Posted: February 2, 2024
JOIN THE ALERT PROJECT: SAFELY LEAVING THE NAVIGATION BRIDGE UNATTENDED FOR PERIODS OF TIME WHILE AT SEA Within the new JIP initiative Alert we will determine the conditions for when it is safe to periodically leave navigation spaces unattended and at the same time examine whether that improves the safety, working and living situation for the crew […]
Events
Publications
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.
@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.
L. Eça, Vaz; Hoekstra, M.
Iterative Errors in Unsteady Flow Simulations: Are they Really Negligible? Conference
20th Numerical Towing Tank Symposium (NuTTS), Wageningen, The Netherlands, 2017.
@conference{Eça2017,
title = {Iterative Errors in Unsteady Flow Simulations: Are they Really Negligible?},
author = {Eça, L., Vaz, G. and Hoekstra, M.},
url = {http://www.marin.nl/web/Publications/Publication-items/Iterative-Errors-in-Unsteady-Flow-Simulations-Are-they-Really-Negligible.htm},
year = {2017},
date = {2017-10-03},
booktitle = {20th Numerical Towing Tank Symposium (NuTTS), Wageningen, The Netherlands},
abstract = {The numerical solution of a statistically steady flow problem is typically obtained in an iterative process. For a given mathematical model, including boundary conditions, the accuracy of the solution is governed by spatial resolution of the grid, spatial discretisation schemes and the convergence tolerance, which says when the solution is considered to have reached a steady state. Next to hardware quality (round-off error), the discretisation error and the iterative error determine the quality of the solution. For unsteady flow problems matters are more complicated. Temporal and spatial resolution have to be chosen carefully in proper balance. Moreover, in high Reynolds number (turbulent) flows, time integration is usually performed with implicit schemes, which require the solution of a non-linear system of equations at each time step. Again a convergence tolerance is needed to decide on when having solved this nonlinear system well enough. Any iterative error propagates to the next time step. How does one guarantee reliability of the results?
This paper summarizes the main results of this first Workshop on Iterative Errors in Unsteady Flow Simulations. It presents a brief description of the proposed test case and the selected quantities of interest and an overview of some of the submitted data. The paper is also meant as an encouragement for participants of the NUTTS symposium to take part in the second edition of the Workshop that will take place at the ASME V&V Symposium of 2018.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
The numerical solution of a statistically steady flow problem is typically obtained in an iterative process. For a given mathematical model, including boundary conditions, the accuracy of the solution is governed by spatial resolution of the grid, spatial discretisation schemes and the convergence tolerance, which says when the solution is considered to have reached a steady state. Next to hardware quality (round-off error), the discretisation error and the iterative error determine the quality of the solution. For unsteady flow problems matters are more complicated. Temporal and spatial resolution have to be chosen carefully in proper balance. Moreover, in high Reynolds number (turbulent) flows, time integration is usually performed with implicit schemes, which require the solution of a non-linear system of equations at each time step. Again a convergence tolerance is needed to decide on when having solved this nonlinear system well enough. Any iterative error propagates to the next time step. How does one guarantee reliability of the results?
This paper summarizes the main results of this first Workshop on Iterative Errors in Unsteady Flow Simulations. It presents a brief description of the proposed test case and the selected quantities of interest and an overview of some of the submitted data. The paper is also meant as an encouragement for participants of the NUTTS symposium to take part in the second edition of the Workshop that will take place at the ASME V&V Symposium of 2018.
This paper summarizes the main results of this first Workshop on Iterative Errors in Unsteady Flow Simulations. It presents a brief description of the proposed test case and the selected quantities of interest and an overview of some of the submitted data. The paper is also meant as an encouragement for participants of the NUTTS symposium to take part in the second edition of the Workshop that will take place at the ASME V&V Symposium of 2018.