Simulating Melting-solidification of Lunar Regolith Particles Using Coupled CFD Methods

Lunar exploration endeavours, such as the Artemis program, demand the study of the behaviour of lunar dust. Lunar landing scenarios involve high-enthalpy interactions with lunar regolith. This work proposes that regolith particles experience a melting mechanism, making a “sticky” partially melted liquid outer layer, leading to unique interactions between regolith and structures on the lunar surface. (Alternate to these next few sentences: An analytical source flow model was used to estimate the flow conditions a certain distance away from a plume. The results for the analytical model were used as boundary conditions for a Computational fluid dynamics (CFD) simulation. The simulation was set up using the Eulerian volume-of-fluid (VOF) method and was used to simulate the melting-solidification of the particle as it interacts with a structure. The VOF model extends one formulated for sand ingestion into aircraft but has been uniquely adapted to study partially-melted regolith impacts. The VOF method was used to capture the solid to partial solid/liquid phase change dynamics of the melting regolith particles. The final paper presents novel studies elucidating dynamic properties of melting regolith. Simulations involve initializing a regolith particle at ambient conditions and the surrounding fluid to rocket plume conditions. Time-varying temperature, melting, aerodynamic character, and shape are extracted. Non-dimensional variables, including Reynolds, Weber, and Ohnesorge numbers, are explored. The outcome of this paper will provide guidance relevant to the fouling of surfaces from partially melted regolith during landings.