Spreading of a Water Drop in an Oil Layer

For the first time, the evolution of the spreading pattern of a fallen water drop over the surface of a cavity and a crown in a deep layer of oil has been traced by high-resolution video and photography. At the stage of active drop submergence, the double layer formed by the contacting surfaces of immiscible fluids is the most rapid component of the flow. Droplets containing both fluids fly out from the tops of the spikes on the edge of the crown. The water covering the inner surface of the cavity and the crown flows unevenly downwards after submergence of the drop. Isolated anhydrous areas, voids, are formed on the surface of the crown and are separated by narrow bands of water, which eventually break up into separate drops. The bulk of the water unevenly submerges to the bottom of the cavity and, at its collapses, remains in the bulk of the liquid in the form of individual fragments, gradually tightening into smooth droplets. The regularities of the temporal changes in the splash height and in the shape of the cavity section are revealed.