A drop of red dye falls into a thin layer of milk, forming a crown splash. Notice the pale edges of the droplets at the rim of the crown; this is milk that has been entrained by the original drop. The rim and satellite droplets surrounding the splash are formed due to surface tension effects, chiefly the Plateau-Rayleigh instability–the same effect responsible for breaking a falling column of liquid into droplets like in a leaking faucet. The instability will have a most unstable wavelength that determines the number of satellite droplets formed. (Photo credit: W. van Hoeve et al., University of Twente)
Celebrating the physics of all that flows