Vapor distribution changes evaporative flux profiles of a sessile droplet

Hypothesis: We propose that during the evaporation of sessile droplets, the evaporative flux profile is primarily influenced by droplet geometry and composition under diffusion-limited conditions. Most studies have focused solely on the evaporation feature from the liquid to the gas phase, neglecting the extent to which the evaporated vapors affect the evaporation process. We hypothesize that if the molecular weight of the evaporated vapors is significantly high or low compared to the ambient gas, it could alter the evaporative flux.Experiments: We employed a direct optical measurement technique, specifically Mach-Zehnder interferometry. This demonstrated that the distribution of evaporated vapor molecules can substantially modify the evaporative flux profile. Findings: Our study discovered that substantial density gradients between vapor and air could either suppress or enhance the evaporative flux, depending on the droplet's orientation. This research offers fresh insights into evaporative fluxes by taking into account the relative vapor concentration and gravitational effects.

Automated summary

Our study demonstrates that the evaporation flux is primarily influenced by the geometry and composition of the droplet under diffusion-limited conditions. Previous research has mainly focused on the evaporation from liquid to gas phase, neglecting the impact of evaporated vapors on the process. We hypothesize that vapor with significantly different molecular weight from the ambient gas can alter the evaporation flux.