Validation of a High-Order Diffuse Interface Multi-Phase Method for High-Speed Droplet Shock Interaction and Impingement

High-speed droplet impingement is a challenging problem involving a wide variety of physical mechanisms, including aero-breakup and phase change. Diffuse interface multiphase methods provide a simple, computationally efficient, and numerically robust approach to model these phenomena. In this work, a high-order numerical solution procedure for the Allaire five-equation model within the in-house solver CHAMPS is validated against currently available numerical and experimental data in one, two, and three dimensions. Simulations were performed with liquid and gas phases and geometries were efficiently modeled using the immersed boundary method. Adaptive mesh refinement was employed to efficiently track important flow features such as shocks and wakes. Recent shock interaction results at Mach 2.4 and Mach 10 were reproduced with a first-order HLLC approach and a higher-order positivity-preserving WCNS scheme introduced by Wong et al. (2021). The same method was applied to a water column impingement at 110 m/s and good agreement with recent numerical results and shadowgraph images was found. Finally, a computationally challenging set of 2D and 3D test cases considering high-speed flows are presented including shock-droplet interaction and impingement on an oblique wedge geometry.