An Application And Study Of Multi-material Flows On Unstructured Moving Grids

The numerical simulation of compressible multi-material fluids has become an increasing important aspect in CFD. My thesis is support by National Natural Science Foundation of China. The project's name is the computational methods and meshes generation involving moving boundaries. In the context, the former advancing front approach is used to generate unstructured grids, and the improved spring method is applied to handle grids' deformation because of their movement. Explicit finite volume cell-center formulation is used to solve multi-material flows based on unstructured moving grids. The HLLC method is presented in the context of arbitrary Lagrangian-Eulerian formulation for solving the unsteady compressible Euler equations. The algorithm can achieve second-order precision in space and forth-order in time. At the interface, by setting the velocity of grid's boundary equal to the velocity of fluid makes sure that the mass across interface is none and then R-H jump condition is satisfied. In order to eliminate oscillatory near the discontinuities, two methods are implemented to deal with flux. One is "ghost fluid method", the other is the method based on Riemann problem solvers. Problems of shock tube, underwater explosion, supersonic missile over water etc are simulated and excited results are obtained.