Lifetime Prediction of Sessile Droplet Evaporation with Coupled Fields

The evaporation of sessile droplets has wide applications in various industrial fields. Therefore, it is important to accurately predict the temporal evolution behavior of sessile droplets during evaporation. In this paper, both theoretical analysis and numerical simulation are carried out to explore the evolution of droplet evaporation, with internal thermocapillary convection, interfacial evaporative cooling, and external natural convection coupled together. It is found that internal thermocapillary convection and external natural convection can promote droplet evaporation, while interfacial evaporative cooling can impede it. When a droplet evaporates in a constant contact radius mode, there is a critical initial contact angle, below which the isothermal model can overestimate the evaporation lifetime, and the critical initial contact angle becomes large with increasing substrate superheat. Finally, when the droplet evaporates in the constant contact angle mode, the "2/3 power law" still holds for transient variation of droplet volume, as predicted by the isothermal model. These findings may help obtain insights into the mechanism of droplet evaporation and provide guidance for inkjet printing and surface cooling.