Simultaneous impact of droplet pairs on solid surfaces

This study investigates the dynamics of simultaneous impact two droplets on a dry substrate. We develop new micro-controlled droplet generator that releases equally sized water simultaneously on-demand, with no trailing droplets. The Weber number, based size and velocity, inter-droplet spacing relative to are varied in ranges 54 155 1.32 2.25, respectively, leading strong interaction spreading lamellae form central uprising sheet, which eventually deposits or breaks into tiny analyse processes for both deposition splashing sheets. Simultaneous high-speed imaging from orthogonal views impacts quantifies three-dimensional structure sheet morphology, including temporal evolution rim-bounded ‘semilunar’ shape, surface waves, rim corrugations finger formation, liquid sheet. characteristics waves instabilities quantified. Novel scaling is developed maximum height, width thickness, considers geometrical constraints mass balance interacting describe good agreement measurements. generates larger than those single-droplet impacts, it occurs due end-pinching fingers at conditions lead only deposition.