Self-organizing hybrid Cartesian grid/solution system for arbitrary geometries
Frank Deister, Ernst Heinrich Hirschel · 18th Applied Aerodynamics Conference · 2000
An automatic adaptive hybrid Cartesian grid generator is presented together with solutions of flows around complicated two- and three-dimensional geometries. The primary computational grid is a Cartesian grid, which is generated based on an octree-data structure. A secondary grid may be added for resolving the boundary layer region of viscous flow around the solid body. It consists of quasi triangular-prismatic cells generated by marching the body surface triangulation outward. A modified unstructured flow solver is applied for the compressible Euier and Navier Stokes equations. For turbulent flows, the eddy viscosity is calculated using the Spalart-Allmaras turbulence model. The grid/solution system distinguishes itself by the attribute of self-organization: starting from the surface triangulation of the body, the system generates the initial hybrid Cartesian grid by itself. After the flow solution is obtained, the system improves the hybrid grid accordingly. This procedure is repeated until all flow characteristics are sufficiently resolved. The cycle runs fully automatically without any user interventions: it depends only on the body geometry and the flow structure. In this sense, the grid is organized by the flow itself. In order to achieve this goal, the adaptation features are manifold.