Particle Flow Physics Modeling for Extreme Environments

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. This process occurs in a combination of "extreme environments" that combine low gravity, little or no atmosphere, rocket exhaust gas flow that is supersonic and partially rarefied, and unusual geological and mechanical properties of highly irregular surface regolith. CFDRC and the University of Florida will deliver unique plume driven erosion simulation software for such environments by combining novel granular physics simulation modules developed by UF with multi-phase gas-granular flow simulation software developed by CFDRC. Granular flow constitutive models, formulated through first-principle 3-D Discrete Element Method particle kinetics and implemented in an efficient Eulerian gas-granular flow solver are the foundation of this software. The fidelity of these simulations will be advanced towards simulating particle compositions with broad shape and size variations. Novel particle kinetics modeling concepts will be applied to formulate granular flow physics models for both, realistic irregular particle shapes and dispersed particle size distributions. Phase I demonstrated the successful implementation and validation of irregular granular shape physics modeling in CFDRC's gas-granular multi-phase flow solver. An approach for extension to poly-disperse particle mixture simulations was also developed. Full integration of these models in Phase II will enable the simulation of gas flow interaction with poly-disperse, irregular shaped particle materials. Extensive verification, validation, and application demonstrations will be performed. The proposed technology development will result in unprecedented computer modeling capability for predicting liberation and flow of realistic granular material compositions in extreme extra-terrestrial environments.