No abstract

Recent interest in the phenomenon of thermocapillary-induced noncoalescence and nonwetting has produced experimental evidence of the existence of a film of lubricating gas that prevents the two surfaces in question (liquid–liquid for noncoalescence; liquid–solid for nonwetting) from coming into contact with one another. Measurements further indicate that the pressure distribution in this film creates a dimpled liquid free-surface. Lubrication theory is employed to investigate the coupled effects of liquid and gas flows for a two-dimensional nonwetting case of a hot droplet pressed toward a cold wall. The analysis focuses on the respective roles of viscous and inertial forces on droplet deformation. Resultant droplet shapes show an influence of gas viscosity maintaining nonwetting and of inertia contributing to a dimple. Previous analyses of thermocapillary-driven flow in liquid layers and droplets model the gas as purely passive which cannot be the case in the present application.