Study of Collision Methodologies for Particle-Laden Flows Relevant for Aerospace Applications

While particle-laden flows are of great interest for a wide variety of applications, accurately accounting for particle–particle collisions can be challenging. In this work, three particle collision strategies based on the hardsphere paradigm (event-driven (EDHS), time-driven (TDHS), and direct simulation Monte Carlo (DSMC)) are considered in order to gain insight into which method is best suited for use in aerospace applications. First, a spatially homogeneous 0-D setup was investigated in the kinetic regime to leverage theoretical results from kinetic theory. While the DSMC method showed excellent agreement with the theoretical kinetic collision rate, both the EDHS and TDHS methods displayed inaccurate collision rates due to an artificially increased particle volume fraction from the use of simulated particle bundles. Next, a particle-laden nozzle setup was considered using the Dust Simulation and Tracking plug-in for the US3D unstructured finite-volume CFD solver. Comparisons of the particle-induced surface erosion on the test article were made with both elastic and inelastic particle collision parameters using the DSMC and TDHS methods. Both the TDHS and DSMC methods agreed extremely well for both the elastic and inelastic setups, although there is a slight discrepancy in the results for the inelastic comparison. Based on the overall results of the two studies in this work, the DSMC method was determined to be the most suitable for aerospace applications (i.e., cases with low volume fractions) because of its accuracy, efficiency, ability to handle arbitrary particle weights, and ease of implementation on parallel architecture.