Octree-advancing front method for generation of unstructured surface and volume meshes

A method is described for the generation of unstructured grids for complex three-dimensional geometrics including multibody domains. A combined octree-advancing front method is presented for generation of the unstructured surface mesh as well as the tetrahedral volume mesh. The unique feature of this generator is that a special octree provides the local length scales of the mesh, which can vary significantly. This octree is automatically created and eliminates the need for a user-constructed background mesh to determine the grid-spacing and stretching parameters. The grid generator is robust, is geometry independent, and requires minimal user interaction. A technique is also presented for generation of anisotropic surface meshes that result in a significant reduction in the number of triangular faces. Automatic local remeshing is also employed to improve the quality of the tetrahedral mesh. The geometry independence of the octree-advancing front method is demonstrated through both surface and volume meshes generated around different complex three-dimensional configurations. The robustness and flexibility of the method is demonstrated through generation of both an all-tetrahedral mesh and the tetrahedral part of hybrid prismatic/tetrahedral grids for viscous hows. The scalability of the generation time is shown through generation of different meshes around the same geometry with various levels of coarseness, Finally, the suitability of the unstructured grids for flow simulations is demonstrated through viscous flow simulations around a high-speed civil transport type of aircraft configuration using a hybrid prismatic/tetrahedral mesh.