Hybrid prismatic/tetrahedral grid generation for viscous flows around complex geometries

Abstract

A method for the generation of hybrid prismatic/tetrahedral grids is described for complex three-dimensional geometries, including multibody domains, and employed for viscous flows around an aircraft. The prisms cover the region close to each body's surface, while tetrahedra are created elsewhere. A special method is presented that allows the generation of single-block, nonoverlapping prismatic meshes even in complex geometries that contain narrow gaps and cavities. Examples of cases treated by this method include wing-engine configurations as well as multi-element wings. The second development is a combined octree/advancing front method for the generation of the tetrahedra of the hybrid mesh. The main feature of this octree-based tetrahedra generator is that it does not require the creation of a background mesh by the user for the determination of the grid-spacing and stretching parameters. These are determined via an automatically generated octree. The hybrid grid generator is robust, geometry independent, and requires no user intervention. The suitability of hybrid meshes for capturing viscous flow phenomena is demonstrated by simulation of viscous flows around a high-speed civil transport type of aircraft configuration. Reduction in computer resources has been substantial, allowing flow simulations to be performed on workstations rather than supercomputers.