二维非结构网格DSMC方法的实现及其应用

Implementation of 2D Unstructured DSMC Method and Its Application

研究了非结构网格 DSMC方法实现的过程 ,将 Bird位置元方案中的子网格思想引入到非结构网格上来 ,只存储子网格的总体标识号 ,做到了利用较少的计算网格提高分子的分辨率和计算精度 ;提出了将面积元坐标搜索算法与交替数字二叉树搜索算法 (ADT)相结合来跟踪模拟分子在网格之间的迁移 ;使用 ADT方法判别分子与物面是否相交 ,节约了计算时间 ;最后对过渡流域高超声速绕流进行了数值试验 ,结果表明这种方法的可行性、高效性及算法的通用性。

The implementation of an unstructured direct simulation Monte-Carlo (DSMC) method is studied and the idea of sub-cell of Bird′s position element method is introduced. ID number of sub-cell of unstructured grid is only stored in computer memory. In order to improve computing efficiency and save running time, an automatic searching method is presented, which is a coupling of area coordinate searching algorithm and alternative digital tree (ADT) searching algorithm. The deterministic criterion for a molecule to reflect on a certain surface element is used by ADT algorithm instead of a probabilistic one. Finally, numerical experiments for hypersonic rarefied gas flow are made. Results show the feasibility, great efficiency and generality of the method.