Impact of Including Mass Convection Effects at Particle Boundaries in a Point-Particle Reaction Model

Ejecta experiments performed at Los Alamos National Laboratory show that liquid particles ejected from a strongly shocked, molten metal surface appear to show abnormal transport behavior if they are ejected into an accepting, hydrogen-based medium with which they can chemically react. These abnormalities are highlighted by a staged deceleration phenomenon in recorded velocimetry data as well as an increasing cloud averaged particle diameter as measured in increasing heights above the original surface. A model was developed to simulate the hydriding reactions occurring with the metal particles as well as to handle flaking of the growing hydride shell which was theorized to be responsible for the staged deceleration traces. This work improves this original model by incorporating the effects of mass convection of the ambient gas around the particles at their boundaries. These boundary effects more realistically capture the gas diffusion through the hydride layer to the reaction front as a function of the particle relative velocity which may be necessary to capture the correct reaction rates for the hydriding process. The improved model is compared to the original model in isolated particle cases as well as simulations of the inspiring experiments in an arbitrary Lagrangian-Eulerian hydrocode to show the effects of the mass convection on the developing hydride layer and in quantities of interest extracted from the experimental data.