Automatic creation of quadrilateral patches on boundary representations

A major long-standing problem in the grid generation field has been the automatic creation of suitable computational grids directly on the boundary representations (BReps) that are produced by computer-aided design (CAD) systems. Traditionally one of the difficulties has been that the BRep is not necessarily consistent with the engineering intent of the designer, but is strongly influenced by the CAD operations used in the generation of the model. This problem has largely been circumvented by the introduction of quilts and chains that are defined so as to be consistent with the engineering intent. The other major difficulty that still exists in the creation of block-structured grids is the decomposition of the quilts into a set of logically-rectangular patches (quad patches) that completely cover the configuration. The objective of this paper is to introduce such a quadrilateral patching technique. This paper describes the process used to automatically generate quad patches, followed by examples from several aerospace configurations. The paper concludes with a description of several benefits of quad patches, namely that they can be used as the basis either for block-structured volume grids or for overset grid systems.