Formation, stability and hydrothermal waves in evaporating liquid lenses

Abstract

We present a fascinating experimental investigation of the formation, stability and thermal patterns of evaporating liquid lenses deposited on an evaporating or non-evaporating liquid pool. The use of infra-red allowed measuring the key parameters of the lens and the pool surface temperature. We unveil the significant interaction of the lens with the underlying liquid in the pool. In particular, the contact line of the lens is deformed very significantly and we ascribe this to the combined buoyancy–thermocapillary convection cells on the surface of the liquid pool, generated by a self-induced evaporative cooling effect. We also demonstrate that the evaporative cooling is ultimately responsible for the formation of the lens, which otherwise would have not formed at ambient temperature. The depth of the pool is shown to be very influential on the stability of the volatile lens and its dynamics.