A combined algorithm for characteristic edge match of hexahedral meshes based on priority nodes and relative position relationships

Boundary matching is an important problem in automatic generation of three-dimensional finite element meshes. In this paper, a combined algorithm for characteristic edge match of hexahedral meshes based on priority nodes and relative position relationships was proposed. The geometric and topologic conditions for characteristic edge (C-edge) match were firstly introduced. Seven types of free facet configurations and corresponding matching rules were established. A C-edge matching algorithm which combined priority nodes with relative position relationships was proposed by introducing priority nodes into the relative position relationship method. The identification method for each level of priority nodes was presented. The basic algorithms and implementation strategies of the combined method were introduced in detail. An effective method for characteristic point (C-point) match was also proposed on the basis of geometric topology and priority nodes. In addition, a method for treating the special sub-surface that intersected itself on a boundary line was proposed. A correction method was correspondingly proposed to deal with the nodes matched on unreasonable C-edges. Several examples of automatic meshing for hexahedral elements were provided to demonstrate the accuracy and effectiveness of the boundary matching algorithms proposed in this paper. The results show that the newly proposed algorithms not only can realize accurate match of mesh boundaries, but also establish reasonable geometric and topologic relationships of matched nodes.