As a laminar column of water falls, slight perturbations cause waviness in the stream. Whenever the radius of the stream decreases, the pressure due to surface tension increases, causing fluid to flow away from the area of smaller radius. This outflow decreases the radius further and drives the stream to break into droplets. The mechanism is called the Plateau-Rayleigh instability. (Photo credit: Mahmoudreza Shirinsokhan)
Jet Breakup
