Coupled Discontinuous Galerkin - Direct Simulation Monte Carlo Simulation of Rocket Plume Impingement on Non-Flat Lunar Surfaces.

A coupled code using Discontinuous Galerkin (DG) and Direct Simulation Monte Carlo (DSMC) methods is employed to simulate axisymmetric impingement of Rocket Plume on Non-Flat Lunar Surfaces[1]. Better resolution of flow discontinuities within the rocket nozzle is attempted with the high order DG approach. A one-way coupling is employed by locating the interface in a high Mach Number region [2]. The coupling is affected by overlapping the continuum and DSMC solution domains at the interface and starting the DSMC particles from the DG Nodal locations at the interface. Geometries such as conoids and paraboloids are employed to model cratered and mounded lunar surfaces. The sensitivity of the shock structures and hence the flow fields to the surface topography is examined. Comparisons are made with results from plume interaction with the flat surface[3]. Among other things, the exhaust-gas mass-flux in the radial direction (perpendicular to the axis of the lander) for the conical surfaces was found to be much more sensitive to the surface slope than that for the parabolic surfaces, and flow reversal past the lander in terms of the mass flux was found to be much higher for the cratered surfaces and the tendency for viscous erosion was found to be much higher for the cratered surfaces.