Aerospace Colloquium

Water entry is a classic historical problem in fluid mechanics, and is often one of the first phenomena related to fluids that children encounter, when they throw stones into a lake or pond. While conceptually simple, water entry is extremely complex and involves air entrainment, surface tension, and multiphase flow even at low speeds. The situation becomes much more complicated as the projectile speed is increased, as shock waves and cavitation play important roles. In this seminar, I will discuss my research group's recent progress investigating water entries at previously un-investigated speeds in excess of 1.5 km/s, which is supersonic even in the liquid water. Our approach involves experiments with a two-stage light gas gun facility as well as high fidelity simulations although I will focus on the experiments. The talk will highlight some interesting phenomena such as cavitation, shock waves, and a supersonic splash. I will also briefly describe some new results from hypersonic free flight experiments using the same facility and highlight important associated diagnostic tools.