LANS Informal Seminar
" Local Topological Modification of Hexahedral Meshes Using Dual-Based Operations: Progress and Application"
DATE: January 17, 2007
TIME: - Description:
SPEAKER: Tim Tautges, MCS
LOCATION: Building 221, Argonne National Laboratory
HOST: Sven Leyffer
Local topological modification is widely used to improve mesh quality after automatic generation of tetrahedral and quadrilateral meshes. These same techniques are also used to support adaptive refinement of these meshes. In contrast, few methods are known for locally modifying the topology of hexahedral meshes. Most efforts to do this have been based on fixed transition templates or global refinement. In contrast, a dual-based "pillowing" method has been used which, while local, is still quite restricted in its application, and is typically applied in a template-based fashion. In this presentation, I will describe the generalization of a dual-based approach to the local topological modification of hex meshes and its application to clean up hexahedral meshes.
A set of three operations for locally modifying hex mesh topology has been shown to reproduce the so-called "flipping" operations described by Bern et. al as well as other commonly-used refinement templates. I will describe the implementation of these operators and their application to real meshes. Challenging aspects of this work have included visualization of a hex mesh and its dual (especially for poor-quality meshes); the incremental modification of both the primal (i.e. the mesh) and the dual simultaneously; and the interactive steering of these operations with the goal of improving hex meshes which would otherwise have unacceptable quality. These aspects will be discussed in the context of improving hex meshes generated by curve contraction-based whisker weaving. Application of these techniques for improving other hexahedral mesh types, for example those resulting from tetrahedral subdivision, will also be discussed.
Please send questions or suggestions to Debojyoti Ghosh: ghosh at mcs dot anl dot gov.