The direct simulation Monte Carlo method using unstructured adaptive mesh and its application

The implementation of an adaptive mesh-embedding (h-re%nement) scheme using unstructured grid in two-dimensional direct simulation Monte Carlo (DSMC) method is reported. In this technique, local isotropic re:nement is used to introduce new mesh where the local cell Knudsen number is less than some preset value. This simple scheme, however, has several severe consequences a;ecting the performance of the DSMC method. Thus, we have applied a technique to remove the hanging node, by introducing the an-isotropic re:nement in the interfacial cells between re:ned and non-re:ned cells. Not only does this remedy increase a negligible amount of work, but it also removes all the di>culties presented in the originals scheme. We have tested the proposed scheme for argon gas in a high-speed driven cavity ow. The results show an improved ow resolution as compared with that of un-adaptive mesh. Finally, we have used triangular adaptive mesh to compute a near-continuum gas ow, a hypersonic ow over a cylinder. The results show fairly good agreement with previous studies. In summary, the proposed simple mesh adaptation is very useful in computing rare:ed gas ows, which involve both complicated geometry and highly non-uniform density variations throughout the ow :eld. Copyright ? 2002 John Wiley & Sons, Ltd.