A free-surface capturing method is implemented in the unstructured-grid finite-volume RANSE flow solver ISIS. The flow is computed on a fixed grid both in the air and the water, and the location of each fluid is determined e.g. by solving a transport equation for a concentration function which is zero in the air and one in the water. The various fluxes appearing in the discretized equations are built using the compressive upwind scheme MGDS, which is based on the Inter-Gamma Differencing Scheme (IGDS) (Jasak, H.; Weller, H.G. (1995), 'Interface tracking capabilities of the Inter-gamma differencing scheme,' Internal Report, Mech.Eng.Dept., Imperial College of Science, London). The data of a Series 60 bare hull were chosen to assess the reliability of this free-surface capturing strategy. Three drift angles (0 deg, 5 deg, and 10 deg) were retained. The k-omega SST turbulence model was employed. The computation was started with the GDS (Gamma Differencing Scheme), and then switched to the compressive MGDS scheme to restore the sharpness of the interface at the end of the computations. Comparison of the computed free-surface elevation fields around the ship hull shows that the compressivity of the discretization scheme still plays a central role even if these results are obtained on very fine grids. Not only the amplitudes of the main divergent waves are modified but the free-surface field computed with MGDS contains many secondary waves inside the Kelvin angle in good agreement with experiments, a behavior which is not simulated by the cheaper GDS scheme.
Free-surface capturing RANSE simulations for a ship at steady drift
RANSE-Simulation der Oberflächenbewegung in der Umgebung eines Schiffs bei konstanter Drift
Ship Technology Research / Schiffstechnik ; 51 , 3 ; 106-122
2004
17 Seiten, 10 Bilder, 1 Tabelle, 15 Quellen
Aufsatz (Zeitschrift)
Englisch
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