Evolution of the ejecta sheet from the impact of a drop with a deep pool

Abstract

Abstract We used optical and X-ray imaging to observe the formation of jets from the impact of a single drop with a deep layer of the same liquid. For high Reynolds number there are two distinct jets: the thin, fast and early-emerging ejecta; and the slow, thick and late-emerging lamella. For low Reynolds number the two jets merge into a single continuous jet, the structure of which is determined by the distinct contributions of the lamella and the ejecta. We measured the emergence time, position and speed of the ejecta sheet, and find that these scale as power laws with the impact speed and the viscosity. We identified the origin of secondary droplets with the breakup of the lamella and the ejecta jets, and show that the size of the droplets is not a good indicator of their origin.