A parallel implicit hole-cutting method based on background mesh for unstructured Chimera grid

As an efficient simulation method for complex configurations and moving boundary problems in computational fluid dynamics, Chimera or overset grid techniques have been widely used in many aspects of aeronautics and astronautics. However, there are still some bottlenecks for the current hole-cutting method to handle large scale mesh, such as memory storage limitation and parallel efficiency. In this paper, a parallel implicit hole-cutting method based on unstructured background mesh is presented. The method is based on the parallel searching of donor cells for all grid nodes. In order to reduce the memory consumption of the searching procedure for the large-scale grids, a global-to-local (GTL) searching strategy as well as the background grid approach is developed. To improve the connectivity of overset domains, a parallel front advancing method is adopted to automatically distinguish the active regions. Finally, the efficiency and effectiveness of the present Chimera grid method are validated by some test cases and applications, including multi-store separation from a fighter and a missile pitching-up maneuvering with rudder deflection under a control command. The numerical results demonstrate the potential for steady and unsteady CFD simulations for complex geometries. (C) 2019 Elsevier Ltd. All rights reserved.