Direct Simulation Monte Carlo Calculations of Three Dimensional Non-Continuum Gas Flows

This paper describes the parallel implementation of a three-dimensional direct simulation Monte Carlo (DSMC) code using the OpenMP procedure on a shared memory multiprocessor computer. A dynamic domain decomposition is performed to maintain load balance among the threads. Performance tests are conducted to evaluate the effect of granularity on efficiency. It is shown that the parallel performance is dependent on the problem size. For larger-scale problems, better efficiency can be expected. Synchronization overhead due to data contention is reduced by re-arranging particle removal procedure. The parallel code is used to simulate flow through a rectangular channel with a high-speed moving wall (Couette flow). For high Knudsen (Kn) numbers, the Couette flow characteristics are found to be very different from their continuum counterparts. ‘Ultimate pressures’ are calculated for a wide range of Kn number flows. The variation of the ultimate pressure with Kn number is computed for given wall speed. Maximum compression ratio is obtained in the transition flow region.