Particle Flow Physics Modeling for Extreme Environments

Abstract

The liberation of particles induced by rocket plume flow from spacecraft landing on unprepared regolith of the Moon, Mars, and other destinations poses high mission risks for robotic and human exploration activities. Manipulation, fluidic transport, and processing of regolith materials for ISRU require a thorough understanding of the granular material response. These processes occur under a combination of “extreme environments” that combine low gravity, little or no atmosphere, with rocket exhaust gas flow that is supersonic and partially rarefied, and unusual geological and mechanical properties of highly irregular surface regolith. In particular, the extra-terrestrial granular regolith materials display granular stresses and fluidic behavior are dominated by their irregular particle shapes and poly-disperse mixture composition that defy any terrestrial experience and current modeling capabilities. An adaptive mesh gas-granular multi-phase flow computational framework has been developed to enable simulations of such granular flows. The flow solver implements a two-fluid model with flow equations for the gas phase and granular phase. Innovative granular phase constituent models have been developed and integrated that address the granular material mechanical stress complexities of irregular, jagged particle shapes and poly-disperse mixtures encountered in extra-terrestrial regolith. The capabilities of the solver are presented and key verification and validation results of the solver are demonstrated.