Comparison of Liquid Metal Ejecta Experiments to Point-Particle Simulations in Reactive Media

Results from ejecta experiments performed at Los Alamos National Laboratory show that molten particles ejected from a strongly shocked metal surface appear to show differing transport behavior depending on whether they chemically react with their accepting medium. Those ejected into an inert medium demonstrate expected deceleration at a nearly constant rate. However, those ejected into a reactive, hydrogen-based medium show a staged deceleration phenomenon in recorded velocimetry data. A working hypothesis is that these reacting ejecta particles form hydride shells in transport and the presence of the shell leads to subsequent physical processes which cause the observed non-monotonic decelerations. The specifics of the physical processes which control this phenomenon are mostly unknown and are of interest for developing accurate models for simulating the trajectories of the metal particles after ejection. This work briefly describes the current-day version of the developed point-particle models for the growth of the hydride shell along with potential shedding of nanoparticles from the evolving hydride shell surface along with any phase changes in the shell. The coupling of the mass and energy transfer of the shed particles to the surrounding continuum flow through a dusty gas approximation is also described. Lastly, simulation efforts comparing the point-particle ejecta framework against experimental data encompassing inert and reactive ejecta, both solid and liquid in nature, are discussed to assess the accuracy and potential pitfalls of the model and its assumptions.