Particle Approaches for Modeling Nonequilibrium Flows using Petascale Computing
"Particle Approaches for Modeling Nonequilibrium Flows using Petascale Computing" -- Deborah Levin, University of Illinois at Urbana-Champaign
When steep gradients occur in the strong shocks of hypersonic flows the use of continuum formulations such as the Navier-Stokes equations is questionable. Instead, the Direct Simulation Monte Carlo (DSMC) method provides a numerical solution to the Boltzmann Equation of transport, particularly for modeling thermochemical nonequilibrium shock dominated flows. In the DSMC method, the flow is modeled by a series of collisions that occur by using simulated particles that each represent a large number of real molecules. The approach is computationally tractable and strongly suited to parallelization because the particle collisions and movement are decoupled. Recently we have implemented an approach with uses octree grids to reduce the cell size only in those regions where the mean free path is small, thus reducing the required number of computational particles. The presentation will summarize the computational challenges in terms of our recent results of scalability using the new octree grid approach.