Visualization of an imploding circular wave front and the formation of a central vertical jet

1. Introduction Implosion of surface waves and the resulting formation of a central vertical water jet happen often in nature; they also provide an important analogy for many physical phenomena. For example, when a heavy solid object impacts on a fluid surface, e.g. such as a meteoroid hitting the planet's ocean, a crater is created, which subsequently begins to pinch radially due to the pressure of the surrounding fluid. The collapsing splash results in a high speed upward jet of water (Gekle et al. 2009). The collapse of this jet is perhaps responsible for producing the subsequent principal tsunami (Mader 2004). This implosion phenomenon can also be observed in underwater explosions, where the collapse of a bubble cavity formed at the epicenter of the explosion will result in a high-speed jet, which often results in the damage or destruction of submarines and ships (Blake et al. 1997). In the shallow water limit, the water wave implosion also occurs analogically in nuclear energy fusion where gasdynamic shock waves are imploded to generate dense plasmas of extremely high temperature at the center (Perry and Kantrowitz 1951). In this short paper, the water wave implosion phenomenon is simulated using a simple gate-type experimental setup and the visualization is carried out by video imaging using a high speed camera and by numerical simulation using Volume of Fluid (VOF) method.