Development and Validation of Hydriding Models for Liquid Metal Ejecta in Reactive Media

Recent experiments performed at Los Alamos National Laboratory show that molten particles ejected from a shocked metal surface show varying and unexpected behavior depending on their ability to chemically react with their accepting medium. Inert molten particles demonstrate expected deceleration behavior during transport with monotonically decreasing velocities. However, liquid particles ejected into a hydrogen-based, reactive environment form hydride shells and demonstrate a staged deceleration behavior in recorded velocimetry data. A current hypothesis is that the presence of these shells leads to subsequent physical processes which cause the observed non-monotonic velocity behavior. The specific details of these controlling physical processes are still not well understood and are of great interest for developing accurate models for simulations of the transport of the ejected metal particles. This work describes developed, point-particle based models meant to capture the effects of phase change in the shell material and shedding of nanometer-sized flakes from the shell surface due to stresses in the expanding shell. The shed shell is coupled to the carrier fluid through appropriate mass and energy transfer mechanisms and is modeled like a dusty gas approximation. Simulation efforts comparing the created ejecta framework against experiments 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 in their current state.