Simulation study on effect of bubbles on evaporation characteristics of sessile droplets

In this study, a bubble droplet evaporation model is developed, which aims to investigate the effect of bubbles on the evaporation characteristics of liquid droplets fixed on a substrate without changing the properties of droplets and external evaporation conditions. Corresponding bubble droplet experiments are carried out to verify the numerical model and its results. The results show that the introduction of bubbles increases the initial volume and surface area of the liquid droplet, and the flow field inside the liquid droplet changes from a single Marangoni flow to a double vortex structure with counterclockwise Marangoni flow and clockwise bubble-induced convection, which enhances the flow and heat transfer. The internal temperature distribution of the liquid droplet is more uneven, and the temperature difference is greater than that of pure liquid droplets during the evaporation process. The droplet evaporation mode will be affected, and the change of the droplet from CCR to CCA evaporation mode is accelerated, resulting in a larger proportion of CCA mode in the entire evaporation process. The evaporation of liquid droplets is accelerated, and the average evaporation rate of bubble droplets with bubble volume ratios of 4%, 7%, and 10% is increased by 17.88%, 32.77% and 53.19%, respectively, compared with pure liquid droplets.