Fine Structure Evolution of the Merging Pattern of a Compound Droplet in the Impact Mode

Abstract

Using the method of high-speed video recording of the merging (coalescence) process of compound drops into deep water, the distribution patterns of the drop’s material over the target fluid’s deformed surface in the splash formation mode are traced during the recording of the fine structure evolution of the flow at the initial stage of the coalescence of compound drops. In the experiments, the droplets’ fall height, droplets’ diameter, and the compound ink-oil drop’s core position relative to its geometric center are varied. Fine structures are observed at all flow stages, starting from the contact of the droplet’s oil shell with the target fluid’s surface, followed by cavity formation, core spreading, and splash formation. Using direct measurements and spectral analysis, the characteristic dimensions of fine flows and structures are estimated.