How Olympic Divers Manipulate the Air Cavity to Reduce Splash

Olympic divers achieve significantly higher scores when they perform a dive that appears splash-less. To accomplish this, they perform a "rip" entry, characterized by seething bubbles and the sound of tearing paper. This is technique involves performing an underwater maneuver, such as the pike save, in which the diver rolls forward at the shoulders and hips after entering the water. While this technique is widespread in competitive diving, there is little research on how their manipulation of the air-water interface leads to a smaller splash. In this study, we develop a simplified single jointed diver model and drive it into a pool of water. The impact is recorded with a high-speed camera and analyzed for underwater kinematics, air cavity development, and splash production. These images are used to investigate how rolling after impact manipulates the air cavity. The model is modified to understand how changing the depth of roll initiation affects the underwater air cavity dynamics. The results of these experiments will be used to validate computational fluid dynamics simulations to further understand the surface dynamics.