Hydrodynamics of a Submerging Drop: Immiscible Liquids

The patterns of mass transfer of aqueous-ink-solution drops of 0.2 and 0.5 cm in diameter which fall freely into vegetable oil are investigated by means of macrophoto and high-speed video techniques over the range of the height of fall from 25 to 65 cm. The double layer formed by the contacting surfaces affects the flow pattern in the drop submerging phase. In this layer a part of the available potential surface energy of fluids is converted into other forms. The geometries of the chevron consisting of oil and the drop mass distribution pattern over the inner crown surface turn out to be similar in the initial flow phase. With time, the cavity and splash shapes and the drop mass distribution patterns that depend on time and the distance of drop fall (drop contact velocity) differ significantly. With the beginning of collapse, the ink-free regions (so-called voids) and outlined by thin filaments of drop matter are formed on the inner crown surface. Then, the filaments disintegrate into fine droplets. The geometry of splashes including those reaching the maximum height over the parameter range considered is traced.