The ejecta sheet generated by the impact of a drop

When a drop impacts on a liquid layer it ejects a thin horizontal sheet of liquid, emanating from the neck region connecting the two liquid masses. Dual-frame imaging and pulsed lasers are used to study the origin, speed and evolution of this ejecta sheet for a range of viscosities. The initial ejecta speed can be more than 10 times the impact velocity of the drop. Visualizations using fluorescent dye show the sheet originating from the underlying liquid layer, not the drop liquid. The sheet undergoes a characteristic instability, bending out of its plane and hitting the bottom layer. For some impact conditions the sheet folds in on itself.