Viscous Implicit Overset Method for High-Speed Compressible Flows

Creating computational grids for complex and/or moving geometries is challenging for high-speed compressible flows, especially when using hexahedral grids for computational fluid dynamics simulations of shocks and boundary layers. One means to simplify grid generation is to use an overset method. In overset methods, multiple individual grids are stacked in layers, and then solution information is exchanged between grid layers at overset boundaries. This allows each geometric feature to be gridded independently, which simplifies grid generation. Overset methods also enable simulation of moving bodies because grid layers can slide through one another. A novel overset method is proposed for high-speed compressible, viscous flows. First, an accurate characteristic-consistent qualitatively stable method is developed to exchange the solution between grid layers. Next, a means for moving overset grids is implemented, including rigid-body dynamics, a conservative cell-unblanking scheme, and a collision detection algorithm. The method is compatible with implicit time-integration methods, which enables much larger simulation time steps, and therefore reduced simulation clock times. The method is parallelized to run on arbitrarily partitioned, unstructured or block-structured computational grids, and the method is validated using canonical test cases. The method is applied to study a store separation case, a shock surfing problem, and cylinder/wall elastic collision.