We considered the impact of small hydrophobic spheres on a water surface. Particular attention was given to characterizing the shape of the resulting air cavity when the cavity collapse is driven principally by surface tension rather than gravity. A parameter study revealed the dependence of the cavity structure on the governing dimensionless groups. A theoretical description based on the solution to the Rayleigh–Besant problem was developed to describe the evolution of the cavity shape and yields an analytical solution for the pinch-off time and the sphere’s depth at cavity pinch-off.

See paper Aristoff & Bush, JFM (2009) .