Surface Mesh Generation for Dirty Geometries by Shrink Wrapping using Cartesian Grid Approach

Abstract

A Cartesian shrink wrapping technique has been investigated in this study to construct triangular surface meshes for three-dimensional dirty geometries. The geometries dealt in this paper are defined by faceted representation with dirtiness such as nonconforming edges, gaps and overlaps. The objective of the proposed technique is to deliver a way constructing triangular surface meshes for upstream solutions in design processes without extensive labors for healing dirtiness in complicated dirty geometries. A Cartesian grid is overlaid onto the dirty geometries and its cells are adaptively refined until target resolution is achieved while recording intersections with geometric facets in cells. An initial watertight shell called the wrapper surface is constructed by selectively extracting the boundary sides of intersected cells. The wrapper surface is improved by a subsequence of operations such as projecting nodes onto geometry, adjusting nodes on the geometry and editing local triangular faces to achieve better approximation. The meshes generated using the presented technique may not be geometrically accurate but their quality is good enough to quickly deliver upstream fluid analysis solutions with significantly reduced engineering time for problems of extreme complexity such as the full underhood fluid/thermal analysis for automobiles. Mesh generation experiments have been carried out for complicated geometries and results from some applications are presented in this paper.