Coalescence cascade is an effect known in fluid dynamics which can be observed -- if you have access to a video...

Coalescence cascade is an effect known in fluid dynamics which can be observed -- if you have access to a video camera with a sufficiently high frame rate -- when a drop of liquid is deposited very gently onto the surface of a layer of the same liquid.

When a droplet impacts a pool at low speed, a layer of air trapped beneath the droplet can often prevent it from immediately coalescing into the pool. As that air layer drains away, surface tension pulls some of the droplet's mass into the pool while a smaller droplet is ejected. When it bounces off the surface of the water, the process is repeated and the droplet grows smaller and smaller until surface tension is able to completely absorb it into the pool.

Watch:
https://www.youtube.com/watch?v=6KKNnjFpGto

Article:
http://math.mit.edu/~bush/?p=588
http://io9.gizmodo.com/5849356/high-speed-video-reveals-the-bizarre-physics-of-an-ordinary-water-droplet

Paper:
http://scitation.aip.org/content/aip/journal/pof2/12/6/10.1063/1.870380

#physics   #fluiddynamics   #coalescencecascade   #waterdroplet