Surface mesh generation for dirty geometries by the Cartesian shrink-wrapping technique

Abstract

A Cartesian shrink-wrapping technique has been investigated in this study to automatically generate triangular surface meshes for 3D dirty geometries. The geometries dealt in this paper are defined by a faceted representation and have flaws such as non-conforming edges, gaps, and overlaps. The proposed technique addresses a way of constructing triangular surface meshes for upstream fluid simulations in design processes without extensive manual labor for healing complicated dirty geometries. The meshing procedure begins by overlaying a Cartesian grid onto the dirty geometries and the Cartesian cells are adaptively refined until a 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 the intersected cells. The wrapper surface is improved by a combination of operations such as projecting nodes onto the geometry, adjusting nodes on the geometry, and editing local triangular faces to achieve a better geometric approximation. The meshes generated using the presented technique may not precisely represent the details of the input geometries, 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.