Cavity dynamics of vertical water entry by air jet

This study investigates the dynamics of cavities formed by the water entry of an impacting air jet. Utilizing a fine tube that continuously injects air and falls freely, we observe the creation and subsequent collapse of air jet cavities. Our experimental observations reveal that these cavities do not undergo a surface seal event, and the Worthington jet exhibits rippling and droplet breakup after deep seal. The behavior of the air jet cavity is influenced by dual Froude numbers, resulting in distinct cavity types. Additionally, we report four cavity seal regimes and identify the mechanisms underlying their pinch-off. To give the mathematical description of the cavity's evolution, we extend the theory in Duclaux et al. [J. Fluid Mech. 591, 1 (2007)] and compare it with our experiments. The theoretical model successfully captures the air jet cavity development and subsequent pinch-off events. locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon Physics Subject Headings (PhySH)Flow-structure interactionsInterfacial flows