Full continuum approach for simulating plume-surface interaction in planetary landings

A high-fidelity computational framework for predicting the interaction of a rocket plume with a dust blanket in an almost vacuum ambient that represents the descent/ascend phase of planetary landing is developed. Compared to the existing continuum frameworks, the developed tool benefits from nonlinear-coupled constitutive relationships obtained using a method of moments approach to tackle the non-equilibrium effects in the rarefied condition. The two-phase flow is modeled in an Eulerian framework that allows for the simulation of a wider range of solid regimes compared to the Lagrangian counterpart. Simulations were conducted to analyze the cratering phenomena and regolith ejecta dynamics. Moreover, the vorticity growth rates were analyzed using a new vorticity transport equation (VTE) by including the bulk viscosity and multiphase terms to demonstrate the contribution of each term to the formation of counterintuitive festooned patterns on the surface owing to jet impingement. This analysis identified a new contributing mechanism responsible for the scour patterns. Although all the investigated terms in the VTE contribute to such patterns, the viscous term has more effect during the entire investigation period. Furthermore, studies on particulate loading, particle diameter, and bed height were conducted to highlight the role of these parameters on brownout phenomena and scour formation patterns. The simulation results depict that the generated vortex core beneath the nozzle is highly dependent on the diameter of the particles as well as the bed height: an increase in the height of the bed and particle diameter can lead to a more favorable brownout status.