Pattern Formation in Moist Convection

We report experiments on Rayleigh-Taylor like instability in a moist convection experiment. We use Sulphur Hexaflouride (SF6) as the working fluid. The experiment was operated across the liquid-vapor coexistence curve. The liquid layer on the bottom plate was heated from below. The vapor evaporating from the liquid-vapor interface condensed on the top plate forming a layer of liquid SF6. This layer underwent a Rayleigh-Taylor like instability, which resulted in the formation of drops that dripped periodically. We observed hexagonal patterns under appropriate conditions . In the absence of a liquid layer on the bottom plate the drops falling from the top plate levitate on the bottom plate due to Leidenfrost effect. These Leidenfrost drops formed large domains with multiple chimneys (multi-connected domains) under appropriate conditions.