Parallel algorithms applied to direct simulation methods

Performing direct simulation Monte Carlo (DSMC) calculations on parallel processors may result in a strongly unbalanced distribution of work. This situation affects the performances leading to very low speedups. We present a method which makes use of adaptive domain decomposition to dynamically distribute the computational work load. The major advantage of this method is the possibility to redistribute the fraction of work which depends on the domain decomposition only. The method has been implemented on a transputer system with up to 8 processors (20 MHz Inmos T800), using the FORTRAN version of Parasoft Express Library for parallel compilers. The problems studied were hypersonic flows of a chemically reacting gas in a two-dimensional domain. The adaptive decomposition method worked well in uniformly distributing the computational work over an arbitrary number of processors and reduced the average execution time by over the 38% in certain cases