An experimental study of the events that follow a drop hitting a small surface

The events that follow a drop hitting a solid surface depend not only on the drop's initial conditions and drop properties but also, in a significant way, on the target-to-drop area ratio. For an impaction surface with a limited-size area, the events are unique and are significantly different from those occurring when the drop hits an infinite flat surface. In this study, we present a wide range of new visual observations focusing on the events that follow a drop hitting a dry solid surface of different small sizes. In particular, our interest is in the deposition, receding breakup, and prompt splash phases. We analyze the results while using non-dimensional groups, graphically depict the various events on a map, and define the borders between them. In addition, we offer a group of criteria that differentiate between events for a wide range of target-to-drop ratio, and Reynolds, and Webber numbers.