ADAPTIVE HYBRID PRISMATIC TETRAHEDRAL GRIDS

Employment of hybrid prismatic/tetrahedral grids is a relatively new approach for viscous flow computations with 3D complex geometries. The body surface is covered with triangles, which provides geometric flexibility, while the structure of the mesh in the direction normal to the surface provides thin prismatic elements suitable for the viscous region. The outermost layer of the prismatic grid is then used as the inner boundary surface for a tetrahedral grid which covers the rest of the computational domain. The hybrid grid is employed for performing Navier-Stokes calculations in the prismatic region near the body and Euler calculations in the tetrahedral regions away from the body. The generation method of hybrid prismatic/tetrahedral grids marches a triangulated surface mesh away from the body to form a semi-unstructured prismatic grid. Tetrahedra are then constructed which are linked directly to the nodes of the outermost prismatic layer. The hybrid grid is locally refined over both the prismatic and tetrahedral regions. Directional embedding of the prisms preserves the structure of the mesh in the normal-to-surface direction.