The Effect of Flow Parameters and Wall Models on Gas-Surface Interactions: A Numerical Investigation of dsmcFoam

TL;DR

This study uses numerical simulations to analyze how flow parameters and wall models influence gas-surface interactions in atmosphere-breathing electric propulsion, revealing the need for improved boundary conditions for accurate modeling.

Contribution

It provides a comprehensive parametric analysis of flow and wall parameters affecting gas-surface interactions using dsmcFoam, highlighting limitations of current boundary conditions.

Findings

Changes in reflection patterns and force density are observed under different conditions.

Current boundary conditions in dsmcFoam are insufficient for accurate physics prediction.

New boundary conditions are needed for better simulation accuracy.

Abstract

Atmosphere-breathing electric propulsion systems harness atmospheric particles as propellant, enabling efficient operation across diverse environmental conditions. To accurately simulate the captured gas flow through the modules, particle-surface interactions must be carefully modelled. To initiate this research, a parametric study is conducted using an extensive simulation matrix to investigate the effects of flow parameters, such as velocity, temperature, species, and angle of attack, and wall model parameters (diffuse fraction/accommodation coefficient) on gas-surface interactions. A simplified test geometry was created to run 2D simulations, where the flow interacts with an adjacent wall positioned perpendicular to one of the inlet patches. In this study, changes in reflection patterns, force density on the surface, and flow properties in the vicinity of the wall are investigated under varying flow and wall conditions using the current boundary conditions of the dsmcFoam solver. Furthermore, the capabilities of dsmcFoam's default boundary conditions in predicting gas-surface interaction physics are evaluated using the results of the simulation matrix. The findings highlight the need for new boundary conditions to accurately replicate interaction physics across various aspects.