Abstract:
Numerical simulations are an important tool for quantitatively understanding hypersonic re-entry flows. Traditional computational-fluid-dynamics simulations that are often used to predict re-entry flows do not include molecular-level processes, such as thermal relaxation and molecular fluctuations, which may influence the performance of re-entry vehicles in extreme hypersonic conditions. Therefore, non-equilibrium molecular-level simulations are required to make accurate predictions in such environments. Molecular gas dynamics is a method to perform high-fidelity simulations of non-equilibrium gas behavior by using computational molecules to represent a gas. This method has been shown to provide a computationally demanding but physically superior way to investigate the relationship between molecular-scale (microscopic) and hydrodynamic-scale (macroscopic) processes in a gas. Such simulations are enabled by Sandia’s highly scalable molecular gas dynamics code SPARTA and NNSA’s exascale computational platforms. We can now accurately simulate non-equilibrium laminar and turbulent flows at length and time scales ranging from molecular to hydrodynamic, thereby shedding new light into unexplored regimes of fluid mechanics. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
Bio:
Dr. Michael Gallis is a distinguished member of the technical staff at Sandia National Laboratories, specializing in rarefied gas dynamics, kinetic theory, and computational fluid dynamics. With over three decades of experience, he has contributed to the development of the Direct Simulation Monte Carlo (DSMC) method and advanced particle-based modeling techniques. He has participated in a number of research projects supporting national security and aerospace applications, such as the Columbia accident investigation and the design of the Mars reconnaissance orbiter. He is a coauthor of the open source DSMC code SPARTA.