Splashes

Particularly familiar everyday examples of complex fluid behavior are splashes made by objects falling into water. When a water drop hits a water surface, at first a symmetrical crater forms. But soon its rim becomes unstable, and several peaks (often with small drops at the top) appear in a characteristic coronet pattern. If the original drop was moving quickly, a whole hemisphere of water then closes in above. But in any case a peak appears at the center, sometimes with a spherical drop at the top. If a solid object is dropped into water, the overall structure of the splash made can depend in great detail on its shape and surface roughness. Splashes were studied using flash photography by Arthur Worthington around 1900 (as well as Harold Edgerton in the 1950s), but remarkably little theoretical investigation of them has ever been made.