The splashing of a drop upon impact is a remarkably complicated phenomenon. Perhaps surprisingly, the air around the impacting drop plays a major role in determining which drops splash and which don’t. Lowering the air pressure, for example, stops a drop from splashing. The layer of air that gets trapped beneath the spreading edge of a drop during impact seems to be responsible for splashing. As seen in the video above, drops that impact on a leaky surface, where air can escape, do not splash. By varying where leakage is possible on the surface, the researchers can localize where trapping the air matters most. There’s a critical radius during the drop’s spread where, without leakage, air will be trapped and cause the drop to splash. (Video credit: Y. Liu et al.)
Drops on a Porous Surface
