In this paper, a virtual mesh refinement (VMR) algorithm for unstructured grids is developed and verified in the parallelized direct simulation Monte Carlo code (PDSC). This algorithm is a two-level virtual mesh refinement, in which the background mesh is refined based on an initial DSMC simulation. The refined cells are arranged in a way similar to the structured grid, which makes the particle tracing on them very efficient, unlike unstructured grids. These virtual cells are used for particle collision and sampling. Only those refined cells which contain the centroid of background cells are used for outputting macroscopic data. Two hypersonic flows with purely quadrilateral and mixed triangular-quadrilateral mesh were used to verify this new mesh-refining algorithm. Results show that the case using VMR can faithfully reproduce the benchmark case with a much reduced computational time.
- Parallel direct simulation Monte Carlo
- Unstructured grid
- Virtual mesh refinement