Figure 1
Alan Stonebraker

Figure 1: The impact of a heavy object on a fluid surface causes a sequence of events leading to the creation of three jets. From left to right in time: The crater first deepens and forms a crown as the object descends. When sufficiently deep, the crater begins to pinch radially due to the pressure of the surrounding fluid. A supersonic jet of air escapes through this collapsing neck. Following the impact of the fluid surface on itself at the neck pinch-off, two fluid jets emerge upward and downward from the pinch. This process illustrates the self-focusing and near singularities that occur when the liquid adjusts to the changing topology of its surface.