Stationary Multistar-Shape Patterns of Water Drops in the Presence of a Temperature Gradient

The evolution of a shape of liquid drops placed onto superheated surfaces has been of interest for several decades, since it is related to various phenomena ranging from atomic nuclear fission to planetary rotation and occurs in numerous industrial processes. We show that a drop locked in a spherical crevice displays multistar-shape patterns with unusually large number of stars n, which can be as high as eleven. The data are interpreted in terms of multiplicative shape disturbances of the drop, which are created by continuously repetitive gas overheats and vapor breakups. This process accompanied by pulsating motions of the drop ends up in a stationary n-star configuration. We also report on the freezing-like behavior of the drop evaporating in a sequence of freezing states. This discovery can be applied to the control over liquid-gas phase transitions at superheated surfaces and can be used for measuring the viscosity and the concentration of particles in suspensions.