Propagation of a kinematic instability in a liquid layer: Capillary and gravity effects

In this experimental and theoretical study a single drop impact onto a liquid layer of finite thickness is investigated. It is focused on the formation, expansion, receding, and merging of a cavity generated by the impact. The shape of the cavity is observed and the evolution of its diameter is measured at various times after impact. The drop velocity, the initial film thickness, and the liquid properties are varied in the experiments. The propagation of the crater diameter in the liquid layer is described theoretically using the kinematic discontinuity approach. The mass and momentum balance equations of the liquid layer account for the inertial effects, surface tension, and gravity. A remote asymptotic solution for the temporal evolution of the crater diameter is obtained. The theoretical predictions agree well with the experimental data.