H-Morph: an indirect approach to advancing front hex meshing

H-Morph is a new automatic algorithm for the generation of a hexahedral-dom inant finite element mesh for arbitrary volumes. The H-Morph method starts with an initial tetrahedral mesh and systematically transforms and combines tetrahedra into hexahedra. It uses an advancing front technique where the initial front consists of a set of prescribed quadrilateral surface facets. Fronts are individually processed by recovering each of the six quadrilate ral faces of a hexahedron from the tetrahedral mesh. Recovery techniques si milar to those used in boundary constrained Delaunay mesh generation are us ed. Tetrahedra internal to the six hexahedral faces are then removed and a hexahedron is formed. At any time during the H-Morph procedure a valid mixe d hexahedral-tetrahedral mesh is in existence within the volume. The proced ure continues until no tetrahedra remain within the volume, or tetrahedra r emain which cannot be transformed or combined into valid hexahedral element s. Any remaining tetrahedra are typically towards the interior of the volum e, generally a less critical region for analysis. Transition from tetrahedr a to hexahedra in the final mesh is accomplished through pyramid-shaped ele ments. Advantages of the proposed method include its ability to conform to an existing quadrilateral surface mesh, its ability to mesh without the nee d to decompose or recognize special classes of geometry, and its characteri stic well-aligned layers of elements parallel to the boundary. Example test cases are presented on a variety of models. Copyright (C) 2000 John Wiley & Sons, Ltd.