Splashing from drop impact into a deep pool: multiplicity of jets and the failure of conventional scaling

We report high-speed optical and X-ray observations of jets formed during the impact of a drop with a deep pool of the same liquid. We show that a scaling that relies entirely on liquid properties, as is conventionally employed, is insufficient to determine the threshold for splashing. In order to determine if the gas properties could account for this deficit, we conducted experiments with different surrounding gases. We find that the splashing threshold depends on the gas's dynamic viscosity, but not its density. We argue that these results are consistent with a thickening of the ejecta caused by the bubble trapped on impact between the drop and the pool. We also show that drop impact can generate a third jet, distinct from the lamella and the ejecta, that produces secondary droplets of an intermediate size.