Drop Impacts on Liquid Layers: Some New Phenomena at the Edges of Parameter Space

Abstract

Here we report experiments on three separate “drop-impact” phenomena. The first phenomena is entirely driven by surface tension whereas the second evolves in the absence of surface tension at the surface of a granular medium. The former of these is realized when a stationary drop of liquid coalesces with a flat layer of the same liquid. This coalescence is observed to take place in steps generating smaller and smaller drops. The latter phenomena occurs when a solid sphere is impacted onto a deep layer of granular medium. The resulting transient crater collapses radially driving up a thin vertical jet of material along the axis of symmetry. This jet is reminescent of Worthington jets which are observed in analogous liquid experiments. The third experiment looks at some intriguing shapes of newly discovered ejecta sheets.