3D simulation of flow with free surface based on adaptive octree mesh system

Abstract

The technique of adaptive tree mesh is an effective way to reduce computational cost through automatic adjustment of cell size according to necessity. In the present study, the 2D numerical N-S solver based on the adaptive quadtree mesh system was extended to a 3D one, in which a spatially adaptive octree mesh system and multiple particle level set method were adopted for the convenience to deal with the air-water-structure multiple-medium coexisting domain. The stretching process of a dumbbell was simulated and the results indicate that the meshes are well adaptable to the free surface. The collapsing process of water column impinging a circle cylinder was simulated and from the results, it can be seen that the processes of fluid splitting and merging are properly simulated. The interaction of second-order Stokes waves with a square cylinder was simulated and the obtained drag force is consistent with the result by the Morison’s wave force formula with the coefficient values of the stable drag component and the inertial force component being set as 2.54.

Keywords

adaptive octree mesh / 3D numerical flume / spatially adaptive multiple particle level set

References

[1] Huang X, Li Shaowu. Spatially adaptive fast particle level set method[J]. Journal of Tianjin University: Science and Technology, 2010, 43(11): 981-987.

[2] Huang X, Li S, Xia Bo. A new 3D numerical model for stream[J]. Acta Oceanologica Sinica, 2010, 32(6): 167-173.

[3] Huang X, Li Shaowu. A two-dimensional numerical wave flume based on SA-MPLS method[J]. Acta Oceanologica Sinica, 2012, 31(3): 18-30.

[4] Huang X, Li Shaowu. Numerical N-S equation solver based on adaptive quadtree mesh[J]. Journal of Tianjin University: Science and Technology, 2013, 46(1): 58-66.

[5] Losasso F, Gibou F, Fedkiw R. Simulating water and smoke with an octree data structure[C]. In: Proceedings of SIGGRAPH2002 Conference. ACM SIGGRAPH. San Antonio, USA, 2002, 457-462.

[6] Losasso F, Fedkiw R, Osher S. Spatially adaptive techniques for level set methods and incompressible flow[J]. Computers and Fluids, 2006, 35(10): 995-1010.

[7] Sethian J. Numerical algorithms for propagating interface: Hamilton-Jacobi equations and conservation laws[J]. Journal of Differential Geometry, 1990, 31: 131-161.

[8] Sumer M, Fredsøe J. Hydrodynamics Around Cylindrical Structures[M], 1997, Singapore: World Scientific.