On the use of euler and crank-nicolson time-stepping schemes for seakeeping simulations in openfoam
Document typeConference report
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The open-source CFD software package OpenFOAM has reached a maturity level such that it is possible to perform seakeeping simulations using the included VOF-based free- surface URANS (Unsteady-Reynolds-Averaged Navier-Stokes) solver (a.k.a interDyMFoam). This paper describes results of seakeeping tests and the experiences obtained while selecting an appropriate combination of spatial and temporal schemes for wave and seakeeping simula- tions in a regular head sea condition. Particular attention has been paid to the accuracy level and the convergence rate of temporal schemes Euler and CrankNicolson since an accurate tem- poral discretization is known to be very important for wave propagations. Here the numerical results confirm the need for at least a 2nd-order temporal scheme. To improve the stability and the robustness of the existing CrankNicolson scheme we customized the code and performed a numerical experiment on the modified CrankNicolson scheme where the off-centering parameter co is non-uniformly distributed in the domain. The results show that when using a simple distri- bution of the co parameter the stability of the CrankNicolson scheme can be restored without having to degrade significantly the numerical order of the scheme. This new approach allows stable simulations to be performed where the incident wave field is propagated more acceptably with a very small decay and, at the same time, keeps the time step large enough to allow the simulations to finish at a reasonable CPU time.
CitationSeng, S.; Monroy, C.; Malenica, S. On the use of euler and crank-nicolson time-stepping schemes for seakeeping simulations in openfoam. A: MARINE VII. "MARINE VII : proceedings of the VII International Conference on Computational Methods in Marine Engineering". CIMNE, 2017, p. 905-920. ISBN 978-84-946909-8-3.
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