1.
Guilherme Vaz Thomas Lloyd, Douwe Rijpkema
Fifth International Symposium on Marine Propulsors smp’17, 2017.
@conference{Lloyd2017,
title = {Computational fluid dynamics prediction of marine propeller cavitation including solution verification},
author = {Thomas Lloyd, Guilherme Vaz, Douwe Rijpkema, Antoine Reverberi},
url = {http://www.marin.nl/web/Publications/Publication-items/Computational-fluid-dynamics-prediction-of-marine-propeller-cavitation-including-solution-verification.htm},
year = {2017},
date = {2017-06-01},
booktitle = {Fifth International Symposium on Marine Propulsors smp’17},
abstract = {This paper analyses the effect of grid refinement on computational fluid dynamics simulations of cavitating propeller flow. Refinement is made both globally, using geometrically similar grids, and locally, by applying adaptive grid refinement. The test case is the E779A propeller operating in uniform inflow conditions in a cavitation tunnel. This allows more computationally efficient steady simulations to be made, permitting a grid uncertainty analysis not previously seen for cavitating flow computations. Unsteady simulations are also presented in order to compare two turbulence modelling approaches. Differences in the discretisation uncertainty in terms of propeller thrust and torque were found to be small between wetted and cavitating flow conditions, although the order of convergence for the cavitating case is lower. Overall the largest effect of grid refinement is found to be in the tip vortex region, where differences in the predicted cavity extents are significant between grids. The use of adaptive grid refinement allows improved capture of tip vortex cavitation with fewer total grid cells, although the cavity extent is limited by increasing eddy viscosity when using RANS. Application of DDES reduces this influence somewhat, motivating further study into the potential of scale-resolving simulations in combination with adaptive grid refinement for vortex cavitation prediction.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
This paper analyses the effect of grid refinement on computational fluid dynamics simulations of cavitating propeller flow. Refinement is made both globally, using geometrically similar grids, and locally, by applying adaptive grid refinement. The test case is the E779A propeller operating in uniform inflow conditions in a cavitation tunnel. This allows more computationally efficient steady simulations to be made, permitting a grid uncertainty analysis not previously seen for cavitating flow computations. Unsteady simulations are also presented in order to compare two turbulence modelling approaches. Differences in the discretisation uncertainty in terms of propeller thrust and torque were found to be small between wetted and cavitating flow conditions, although the order of convergence for the cavitating case is lower. Overall the largest effect of grid refinement is found to be in the tip vortex region, where differences in the predicted cavity extents are significant between grids. The use of adaptive grid refinement allows improved capture of tip vortex cavitation with fewer total grid cells, although the cavity extent is limited by increasing eddy viscosity when using RANS. Application of DDES reduces this influence somewhat, motivating further study into the potential of scale-resolving simulations in combination with adaptive grid refinement for vortex cavitation prediction.
2.
Guilherme Vaz, Thomas Lloyd; Gnanasundaram, Arun
Improved Modelling Of Sheet Cavitation Dynamics On Delft Twistll Hydrofoil Conference
VII International Conference on Computational Methods in Marine Engineering, 2017.
@conference{Vaz2017,
title = {Improved Modelling Of Sheet Cavitation Dynamics On Delft Twistll Hydrofoil},
author = {Guilherme Vaz, Thomas Lloyd and Arun Gnanasundaram},
url = {http://www.marin.nl/web/Publications/Publication-items/Improved-Modelling-Of-Sheet-Cavitation-Dynamics-On-Delft-Twistll-Hydrofoil.htm},
year = {2017},
date = {2017-05-01},
booktitle = {VII International Conference on Computational Methods in Marine Engineering},
abstract = {In this paper, unsteady viscous-flow cavitation predictions for a 3D hydrofoil are performed using three different approaches: 1) a pure RANS method; 2) a RANS method including an eddy-viscosity “Reboud” correction; 3) a DDES Scale-Resolving-Simulation approach. Both wetted and cavitating flow conditions are analysed and compared with experimental data. The accuracy of these approaches is scrutinised in terms of integral quantities, cavity dynamics, different background principles, and the influence of grid refinement. Low numerical uncertainties have been obtained for wetted flow conditions, but a somewhat large deviation on the wing loading has been observed when compared with experimental results. For the cavitating flow case, the RANS calculations do not accurately simulate the cavity dynamics. The RANSReboud correction improves the fidelity of the calculations at increased numerical demands and decreased robustness. The DDES approach leads to improved dynamics, slightly less accurate cavity shedding mechanism, at lower computational cost. The cavity extents are underpredicted for all methods and conditions used, when compared with the available experimental data.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
In this paper, unsteady viscous-flow cavitation predictions for a 3D hydrofoil are performed using three different approaches: 1) a pure RANS method; 2) a RANS method including an eddy-viscosity “Reboud” correction; 3) a DDES Scale-Resolving-Simulation approach. Both wetted and cavitating flow conditions are analysed and compared with experimental data. The accuracy of these approaches is scrutinised in terms of integral quantities, cavity dynamics, different background principles, and the influence of grid refinement. Low numerical uncertainties have been obtained for wetted flow conditions, but a somewhat large deviation on the wing loading has been observed when compared with experimental results. For the cavitating flow case, the RANS calculations do not accurately simulate the cavity dynamics. The RANSReboud correction improves the fidelity of the calculations at increased numerical demands and decreased robustness. The DDES approach leads to improved dynamics, slightly less accurate cavity shedding mechanism, at lower computational cost. The cavity extents are underpredicted for all methods and conditions used, when compared with the available experimental data.
2017
Guilherme Vaz Thomas Lloyd, Douwe Rijpkema
Fifth International Symposium on Marine Propulsors smp’17, 2017.
Abstract | Links | BibTeX | Tags: adaptive grid refinement, cavitation, DDES, RANS, verification
@conference{Lloyd2017,
title = {Computational fluid dynamics prediction of marine propeller cavitation including solution verification},
author = {Thomas Lloyd, Guilherme Vaz, Douwe Rijpkema, Antoine Reverberi},
url = {http://www.marin.nl/web/Publications/Publication-items/Computational-fluid-dynamics-prediction-of-marine-propeller-cavitation-including-solution-verification.htm},
year = {2017},
date = {2017-06-01},
booktitle = {Fifth International Symposium on Marine Propulsors smp’17},
abstract = {This paper analyses the effect of grid refinement on computational fluid dynamics simulations of cavitating propeller flow. Refinement is made both globally, using geometrically similar grids, and locally, by applying adaptive grid refinement. The test case is the E779A propeller operating in uniform inflow conditions in a cavitation tunnel. This allows more computationally efficient steady simulations to be made, permitting a grid uncertainty analysis not previously seen for cavitating flow computations. Unsteady simulations are also presented in order to compare two turbulence modelling approaches. Differences in the discretisation uncertainty in terms of propeller thrust and torque were found to be small between wetted and cavitating flow conditions, although the order of convergence for the cavitating case is lower. Overall the largest effect of grid refinement is found to be in the tip vortex region, where differences in the predicted cavity extents are significant between grids. The use of adaptive grid refinement allows improved capture of tip vortex cavitation with fewer total grid cells, although the cavity extent is limited by increasing eddy viscosity when using RANS. Application of DDES reduces this influence somewhat, motivating further study into the potential of scale-resolving simulations in combination with adaptive grid refinement for vortex cavitation prediction.},
keywords = {adaptive grid refinement, cavitation, DDES, RANS, verification},
pubstate = {published},
tppubtype = {conference}
}
This paper analyses the effect of grid refinement on computational fluid dynamics simulations of cavitating propeller flow. Refinement is made both globally, using geometrically similar grids, and locally, by applying adaptive grid refinement. The test case is the E779A propeller operating in uniform inflow conditions in a cavitation tunnel. This allows more computationally efficient steady simulations to be made, permitting a grid uncertainty analysis not previously seen for cavitating flow computations. Unsteady simulations are also presented in order to compare two turbulence modelling approaches. Differences in the discretisation uncertainty in terms of propeller thrust and torque were found to be small between wetted and cavitating flow conditions, although the order of convergence for the cavitating case is lower. Overall the largest effect of grid refinement is found to be in the tip vortex region, where differences in the predicted cavity extents are significant between grids. The use of adaptive grid refinement allows improved capture of tip vortex cavitation with fewer total grid cells, although the cavity extent is limited by increasing eddy viscosity when using RANS. Application of DDES reduces this influence somewhat, motivating further study into the potential of scale-resolving simulations in combination with adaptive grid refinement for vortex cavitation prediction.
Guilherme Vaz, Thomas Lloyd; Gnanasundaram, Arun
Improved Modelling Of Sheet Cavitation Dynamics On Delft Twistll Hydrofoil Conference
VII International Conference on Computational Methods in Marine Engineering, 2017.
Abstract | Links | BibTeX | Tags: cavitation, DDES, Delft Foil, RANS, Reboud-correction, ReFRESCO
@conference{Vaz2017,
title = {Improved Modelling Of Sheet Cavitation Dynamics On Delft Twistll Hydrofoil},
author = {Guilherme Vaz, Thomas Lloyd and Arun Gnanasundaram},
url = {http://www.marin.nl/web/Publications/Publication-items/Improved-Modelling-Of-Sheet-Cavitation-Dynamics-On-Delft-Twistll-Hydrofoil.htm},
year = {2017},
date = {2017-05-01},
booktitle = {VII International Conference on Computational Methods in Marine Engineering},
abstract = {In this paper, unsteady viscous-flow cavitation predictions for a 3D hydrofoil are performed using three different approaches: 1) a pure RANS method; 2) a RANS method including an eddy-viscosity “Reboud” correction; 3) a DDES Scale-Resolving-Simulation approach. Both wetted and cavitating flow conditions are analysed and compared with experimental data. The accuracy of these approaches is scrutinised in terms of integral quantities, cavity dynamics, different background principles, and the influence of grid refinement. Low numerical uncertainties have been obtained for wetted flow conditions, but a somewhat large deviation on the wing loading has been observed when compared with experimental results. For the cavitating flow case, the RANS calculations do not accurately simulate the cavity dynamics. The RANSReboud correction improves the fidelity of the calculations at increased numerical demands and decreased robustness. The DDES approach leads to improved dynamics, slightly less accurate cavity shedding mechanism, at lower computational cost. The cavity extents are underpredicted for all methods and conditions used, when compared with the available experimental data.},
keywords = {cavitation, DDES, Delft Foil, RANS, Reboud-correction, ReFRESCO},
pubstate = {published},
tppubtype = {conference}
}
In this paper, unsteady viscous-flow cavitation predictions for a 3D hydrofoil are performed using three different approaches: 1) a pure RANS method; 2) a RANS method including an eddy-viscosity “Reboud” correction; 3) a DDES Scale-Resolving-Simulation approach. Both wetted and cavitating flow conditions are analysed and compared with experimental data. The accuracy of these approaches is scrutinised in terms of integral quantities, cavity dynamics, different background principles, and the influence of grid refinement. Low numerical uncertainties have been obtained for wetted flow conditions, but a somewhat large deviation on the wing loading has been observed when compared with experimental results. For the cavitating flow case, the RANS calculations do not accurately simulate the cavity dynamics. The RANSReboud correction improves the fidelity of the calculations at increased numerical demands and decreased robustness. The DDES approach leads to improved dynamics, slightly less accurate cavity shedding mechanism, at lower computational cost. The cavity extents are underpredicted for all methods and conditions used, when compared with the available experimental data.