Degenerate Hex Elements

Abstract

Automatic, all-hex meshes are required in many environments. However, current methods can produce unacceptable results where geometric features or topologic connectivity impose limiting constraints. Collapsing a small number of edges or faces in an all- hex mesh to produce degenerate hex elements may be sufficient to turn an otherwise unusable mesh into an adequate mesh for computational simulation. We propose a post-processing procedure that will operate on an existing all-hex mesh by identifying and collapsing edges and faces to improve element quality followed by local optimization-based smoothing. We also propose a new metric based upon the scaled Jacobian that can be used to determine element quality of a degenerate hex element. In addition we illustrate the effectiveness of degenerate elements in analysis and provide numerous meshing examples using the sculpt meshing procedure modified to incorporate degeneracies.