Hierarchical unstructured mesh generation

An unstructured mesh generation method is described that uses a hierarchical tree structure and recursive cell subdivision to discretize regions around complicated geometries. The method employs a volume-to-surface approach, starting with a Cartesian-aligned and hexahedral-shaped root cell. Recursive subdivision is then used to resolve geometric features. Multiple element shapes are employed, but hexahedral-shaped elements are preferred. Body-conforming meshes are produced and viscous-type spacing is achievable near surfaces. A unique multigrid smoothing strategy is employed to produce high quality elements. Solution based mesh adaptation is also possible and is demonstrated on a two-dimensional example problem.