Coupled Continuum-Rarefied-Granular Flow Modeling for Plume-Surface Interaction in Low-Pressure Environments

Detrimental environments from plume-surface interaction (PSI) during spacecraft propulsive landing include dust lofting, regolith particle ejecta stream obscuration, and debris transport that can threaten the lander and nearby assets. Design of mitigative strategies requires detailed understanding of the characteristics, behavior, and trajectories of ejected particles and surface erosion during the landing phase. For landings in low-pressure and rarefied conditions, evolving PSI physics traverse a complex mixed continuum-rarefied regime which defies analysis using existing state-of-the-art methods. Current PSI predictions have made great strides, but they fall short of simultaneously resolving the underlying continuum, granular, and rarefied flow physics required for accurate characterization of the landing environment. This SBIR will develop and deliver an innovative computational architecture for prediction of PSI in low-pressure and rarefied environments within the massively parallel Loci framework. Recent advances by CFD Research in coupling: (1) continuum and rarefied; (2) gas-granular and rarefied; and (3) continuum and gas-granular predictive methodologies will be leveraged and built upon to enable a coupled continuum-rarefied-granular modeling capability. This first-of-its-kind enabling technology will help improve understanding of PSI in low-pressure and rarefied propulsive landing environments including time-evolving cratering, erosion, and ejecta transport. Phase I will establish proof-of-concept and demonstrate three-way solver coupling for PSI at Lunar conditions including runtime adaptive algorithm selection based on locally evolving physics. In Phase II, the capabilities for detailed investigations into PSI at low-pressure conditions will be matured, and validations against NASA Physics Focused Ground Test (PFGT) data will be performed.