Table 1. Classification of the Collision Regimes.

regime	topology	Weber number	result
bouncing6,13,26	droplet sides facing each other flatten during approach; build-up of ambient gas pushes droplets away from each other	very low (∼100)	two separate droplets
coalescence27−29	droplets merge with little to no deformations during collision	low (∼101)	one stable droplet
stable collision26	formation of a disc during collision	low to moderate (∼102)	one stable droplet
holes6	formation of a disc with a rim during collision; formation of holes in the disc; formation of a torus-like geometry before droplet formation	high (∼103)	one stable droplet
shattering6	formation of a disc with a rim during collision; formation of holes in the disc; breakup of the disc and the rim	very high (∼103)	many satellite droplets