Simulations of High-Speed Droplet Impingement with a Dispersed Phase Model

Accurately simulating high-velocity droplet impingement at hypersonic speeds is a challenging task as it creates extreme flow conditions characterized by (likely) negative to gigapascal pressure regimes. Another aspect that has drawn less attention is the challenge of dealing with the different phases that are created during impact, notably not only liquid, vapor and gas phases. It has been theorized that, during impingement, the ejected mass atomizes, generating a dispersed phase which alters the fluid dynamic behavior drastically. Characterization of each individual micro-droplet in the dispersed phase is not computationally feasible, hence a specific variant of the 7-equation model, the dense-dilute model by Saurel et al. 2017, has been implemented and validated for shock-liquid/dispersed phase interactions and proposed as a way to model high-speed droplet impingement. A hypervelocity droplet impingement simulation is showcased, demonstrating how velocity non-equilibrium is of paramount importance to accurately capture the splashing dynamics observed in experiments.