Multiscale Particle-Continuum Simulations of Hypersonic Flow over a Planetary Probe

Abstract

A modular particle-continuum numerical method is used to simulate the flow over a 70 deg blunted cone planetary probe geometry under various steady-state hypersonic conditions. The conditions studied correspond to low global Knudsen number flow where hypersonic velocities induce a large range of temporal and spatial scales that must be modeled. The modular particle-continuum algorithm loosely couples direct simulation Monte Carlo and Navier-Stokes methods, which operate in nonequilibrium and continuum regions, respectively. In addition, particle and continuum regions have different mesh densities and are updated using different sized time steps. Modular particlecontinuum simulations are shown to reproduce the heating rates, velocity slip, and thermal nonequilibrium on the probe surface, as well as the flowfield properties predicted by the direct simulation Monte Carlo method with high accuracy. For the first time, such a hybrid particle-continuum method is shown to achieve high accuracy while achieving an order of magnitude decrease in required computational time and memory compared with pure particle simulation. The modular particle-continuum simulations agree well with Navier-Stokes simulations and experimental measurements in the dense forebody flow. In the rarefied wake of the planetary probe, the modular particle-continuum results are in better agreement with experimental measurements than Navier-Stokes simulations.

Computational study of collisions between O(3P) and NO(2Π) at temperatures relevant to the hypersonic flight regime

“…The chemistry near the surface of such vehicles typically involves highly nonequilibrium conditions with vibrational and rotational temperatures reaching several thousand Kelvin. 7 The gas-phase and surface reactions and energy transfer at these temperatures are essentially uncharacterized and the experimental methodologies capable of probing them are not well established. Una) Present address: Institute of Materials and Environmental Chemistry, MTA Research Centre for Natural Sciences, Budapest, Hungary, Magyar tudósok körútja 2, Budapest, 1117 Hungary.…”

Communication: Equilibrium rate coefficients from atomistic simulations: The O(3P) + NO(2Π) → O2(X3Σg−) + N(4S) reaction at temperatures relevant to the hypersonic flight regime

“…Near the surface of such vehicles, highly non-equilibrium conditions will be present with vibrational and rotational temperatures independently reaching several thousand Kelvin. 4 The gas-phase, surface reactions, and energy transfer at these temperatures are essentially uncharacterized and the experimental methodologies capable of probing them are not well established. In this respect, theoretical and validated computational approaches become a valuable complement to experiments.…”

Application of a Modular Particle-Continuum Method to Partially Rarefied, Hypersonic Flow

“…In general the MPC method has improved agreement with full DSMC results from the initial CFD result across the entire flow field. To compensate for the inability to model rotational nonequilibrium within the continuum solver, this MPC simulation used a more restrictive rotational nonequilibrium parameter in compression regions of Kn ROT−NEQ = 5 × (T TRA − T ROT ) /T ROT [10,2]. Fig.…”