A Parallel Overset Adaptive Cartesian/Prism Grid Method for Moving Boundary Flows

The use of overset grids in CFD started more than two decades ago, and has achieved tremendous success in handling complex geometries[6]. In particular, overset grids have the advantage of avoiding grid remeshing when dealing with moving boundary flow problems. In this paper, two particular unstructured grids are advocated for moving boundary flow simulation, i.e., the use of overset adaptive Cartesian/prism grids. Semi-structured prism grids are generated around solid walls. These prism grids then overlap a single adaptive Cartesian background grid. With the adaptive Cartesian grid, the mesh resolution of the prism grid near the outer boundary can easily match that of the oversetting Cartesian grid cells. In addition, the tree-based data structure of the Cartesian grid can be used efficiently in hole-cutting and donor cell identification. In order to expedite the simulations, the entire solver was made capable of running in parallel. The overset adaptive Cartesian/prism grid method is tested for both steady and unsteady flow computation. It is demonstrated that moving boundary flow computations can be automated with minimum user interferences.