Anyone who has drizzled honey or another viscous fluid onto a surface is familiar with the rope-like coiling behavior of some liquids. But did you know that same instability can create spirals of bubbles like in this photo? Such behavior is only seen for a narrow range of parameters within the gravitational regime of liquid coiling. As the liquid falls, the center of coiling precesses along its own circle with a frequency much smaller than that of the coiling itself. This means that new coils do not fall exactly on top of old ones, trapping air bubbles between them. As the pile of coils collapses under gravity, the bubbles are carried outward, creating beautiful spiral patterns. (Photo credit: M. Habibi et al.)
Celebrating the physics of all that flows