Numerical Study of High-Mach Water Droplet Aerobreakup and Impingement

Abstract

The deformation, breakup, and shock dynamics of liquid droplets in extreme compressible environments are investigated using a combination of high-fidelity experiments and advanced numerical simulations. Studied configurations include aerobreakup in the stagnation region of high-Mach (3–5) projectile flows, and high-speed droplet impingement on solid surfaces. Experiments conducted at Stevens Institute of Technology use acoustically levitated water droplets and high-speed shadowgraphy or Schlieren imaging to capture transient flow structures and shock interactions. Numerical simulations employ the Allaire five-equation model with high-order schemes and a dense–dilute seven-equation model incorporating velocity non-equilibrium effects, implemented in the in-house CHAMPS solver. Results indicate that early-time aerobreakup is governed by inertial dynamics, with minimal influence from viscosity or surface tension. In the impingement case, long-time shock morphology is primarily shaped by the reflection of the droplet’s own shock wave rather than jet-induced effects. Strong agreement is observed between simulations and experimental data. Additional insights are offered into aerobreakup mass loss mechanisms, Mach number insensitivity, and the importance of non-equilibrium modeling to capture post-impingement jetting dynamics. These findings enhance understanding of multiphase flow interactions in high-speed regimes and support the development of validated computational tools for aerospace and defense applications.