Modeling the closure of cavities at very high impact speed

Bodies impacting the water at high Weber numbers (We) open a gas-filled cavity. Previous work (e.g., Duclaux et al. (2007), Aristoff & Bush (2009)) has described the closure regimes of these cavities over several decades of We. Although additional closure regimes do not arise at larger We, the closure dynamics of very high-speed impact cavities are not well-predicted by existing models. In particular, the mass influx to the cavity from the atmosphere and its interaction with the pressure inside the cavity must be explicitly treated. The role of vaporization will also be described. By comparing model results to experimental closure time and pressure data, we find that a Bernoulli-like model for the restoring force near the free-surface is likely inappropriate at high speeds, but that models based on the local thermodynamics do a good job of predicting near-surface behavior.