Evaporation-driven coalescence of two droplets undergoing freezing

Abstract

We examine the evaporation-induced coalescence of two droplets undergoing freezing by conducting numerical simulations employing the lubrication approximation. When two sessile drops undergo freezing in close vicinity over a substrate, they interact with each other through the gaseous phase and the simultaneous presence of evaporation/condensation. In an unsaturated environment, the evaporation flux over the two volatile sessile drops is asymmetric, with lower evaporation in the region between the two drops. This asymmetry in the evaporation flux generates an asymmetric curvature in each drop, which results in a capillary flow that drives the drops closer to each other, eventually leading to their coalescence. This capillary flow, driven by evaporation, competes with the upward movement of the freezing front, depending on the relative humidity in the surrounding environment. We found that higher relative humidity reduces the evaporative flux, delaying capillary flow and impeding coalescence by restricting contact line motion. For a constant relative humidity, the substrate temperature governs the coalescence phenomenon, and resulting condensation can accelerate this process. Interestingly, lower substrate temperatures are observed to facilitate faster propagation of the freezing front, which, in turn, restricts coalescence.

36 pages, 17 figures. arXiv admin note: text overlap with arXiv:2312.03271

References in corpus (5)

• Universality of Tip Singularity Formation in Freezing Water Drops
• Viscous to Inertial Crossover in Liquid Drop Coalescence
• Vapor-Induced Motion of Liquid Droplets on an Inert Substrate
• Effects of Asymmetric Cooling and Surface Wettability on the Orientation of the Freezing Tip
• Intricate Evaporation Dynamics in Different Multi-Droplet Configurations

Cited by in corpus (1)

• Marangoni-driven freezing dynamics of supercooled binary droplets