Phase structure and its temporal evolution under growing single vapor bubble

Abstract

A vapor bubble's footprint on a heated surface is composed of dry and wet regions, and their temporal evolution is governed by several forces, such as gravity, vapor inertia, viscous friction, and capillarity. In this Letter, we derive three types of relations that depict the dynamic variations in the length scales for the bubble base, dry area, and thin liquid film under a single vapor bubble. The proposed relations are validated using measurement results from clear images of the phase structure captured by high-speed visualization. Here, we reveal that the viscous friction is a dominant force acting on the bubble expansion process; however, it has been previously ignored for simplicity in dealing with the classical Rayleigh equation. Additionally, the critical role of the liquid wetting character in the vicinity of the moving triple phase line is illuminated to quantify the dry area dynamics. Finally, we find an analytic expression to obtain the thickness profile of the thin liquid film under a bubble based on the well-known Landau and Levich liquid coating theory.