Unstructured Grid Generation Using Interactive Three-Dimensional Boundary and Efficient Three-Dimensional Volume Methods

AIAA-93-3452-CP, AIAA, pp.409-419, 1993

MESHING
RESEARCH
CORNER

Timothy D. Gatzke: McDonnel Douglas Corp. St. Louis, Missouri USA
Nigel P. Weatherill: University College of Swansea Swansea, LTK

Abstract
The time required to generate grids for a complex configuration limits the usefulness of CFD in meeting tight project schedules. Unstructured grids are a potential solution to this problem, since the generation of unstructured grids is often less time consuming than generation of structured grids. Unstructured grids can fit more naturally into very complex regions than structured grids. Since there is no inherent structure in the set of grid points, unstructured grids can be easily adapted by adding or deleting points.

This paper will describe the integration of an unstructured grid generation capability into an interactive graphical grid generation system for generating 3-D boundary grids and an efficient 3-D volume grid generation method. Both methods are based on a Delaunay approach with an automatic point creation algorithm. Unstructured surface grid generation is performed interactively on individual geometric surfaces. The individual unstructured surface grids are combined to form the boundary grid of a 3-D region. The 3-D volume method generates the volume grid and ensures that the bounding surface of the domain is contained in the triangulation. One major advantage of the method is the computational speed with which 3-D unstructured volume grids can be generated. It will be shown that it is possible to generate on the order of a million tetrahedral elements in a matter of CPU minutes on workstations of modest computational capabilities, and hence is ideally suited to an interactive environment. The method will be demonstrated for realistic aircraft shapes, including complete configurations.