Investigation on the Hybrid NS-DSMC Simulation of a Nozzle Flow Ionization in a Rarefied Atmosphere using a Post-computation Approach

Abstract

The present work aims to enhance a hybrid Navier-Stokes (NS) and Direct Simulation Monte Carlo (DSMC) methodology with the possibility of computing multispecies reactive flow, enabling the simulation of plasma in multiscale continuous and rarefied flows. A particular interest is the electron density field resulting from the ionization of the flow, answering a need to predict radio communication attenuation at high altitude between rockets and ground stations. Two main hypotheses are proposed to achieve this goal. The first one is that the flow expansion is supposed to be driven by the major species, and the influence of ions and electrons is negligible. The second one is that diffusive effects are neglectable due to the supersonic speed of the flow. These hypotheses allow to post-compute the minor species along streamlines taken from the flow solution using a Lagrangian thermochemical solver rather than natively calculating them, as handling such species in a DSMC simulation is complex. This study investigates these hypotheses on a simple thruster geometry to evaluate and validate the post-computation of the plasma. The obtained widen plume is in agreement with previous study expectation of the increased jet flow expansion angle in a rarefied atmosphere.