| The use of overset grids in CFD started more than two decades ago and has achieved tremendous success in handling complex geometries. In particular, overset grids have the advantage of avoiding grid re-meshing when dealing with moving boundary flow problems. Traditionally the overset grid approach named the chimera approach was mainly used for structured grids to simplify the grid generation process.; In this report, two particular unstructured grids are advocated for moving boundary flow simulation, i.e., the use of overset adaptive Cartesian/prism grids. An algorithm using the algebraic grid generation process was developed to construct semi-structured prism grids are around solid walls. These body fitted 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. For a moving grid, it is necessary to readapt the Cartesian grid frequently. The overset adaptive Cartesian/prism grid method is tested for both steady and unsteady flow computations at a variety of Reynolds numbers. It is demonstrated that moving boundary flow computations can be carried out with minimum user interferences. |
