Benchmark verification of PIC-DSMC programs

We examine a number of common verification and benchmark problems for Particle-in-Cell and Direct Simulation Monte Carlo codes. Since results, including convergence rates, comparison to analytic solutions, and code-to-code comparisons, for these problems are often used as evidence of correctness for simulation codes, it is necessary to understand what successful verification using one or more of these problems implies about the correctness of the simulation code. To that end, a series of benchmark problems is performed in Aleph, a PIC-DSMC code developed at Sandia National Laboratories, including both at the canonical numerical parameters and others where verification should fail. The results presented suggest that improvements and extensions to current benchmark problems and additional problem specifications would benefit existing and future codes thereby providing greater confidence in predictive results.