Intertwined effects of solidification and impact: Instability, fingering, and satellite drop ejection

Upon impact of a liquid drop on a smooth solid surface, lamella spreads and sequentially detaches from bulk contact line. Fingering and ejecting a thin-liquid sheet and satellite drops render those phenomena aesthetically pleasing and mathematically challenging. Though vast literature investigates isothermal splashing dynamics, this study explores lamella extension and its levitation affected by solidification mechanism, an interplay of fluid dynamics, heat transfer, and phase transition with its broad occurrence in nature and industry. Phenomenological observations and theoretical explanation are presented on the high-resolution spatiotemporal splashing physics at the proximity to dynamical contact line. Here, impacting hexadecane droplets on subcooled glass surfaces are experimentally studied with ranges of Weber number from 10.0 to 800 and Stefan number from 0.01 to 0.15. While adjusting substrate temperature, splashing dynamics is controlled and yield unique patterns from thin-sheet to prompt splash, but suppressed eventually with increasingly elevated Stefan number. We - Ste nomogram is constructed based on splash outcomes and instability threshold determined. This work aims to ultimately reveal how solidification interferes with splashing dynamics.