Simulation of influencing factors of evaporation progress of sessile droplets based on dynamic contact angle

In the case of integrating the dynamic contact angle model, droplet evaporative cooling effect, vapor diffusion in the air domain and Marangoni effect, the two-dimensional axisymmetric model is used to study the evaporation process of sessile droplets on the horizontal substrate, and the effects of environmental factors, substrate properties and droplet thermophysical properties on droplet evaporation are analysed. The results show that the Marangoni flow plays a dominant role in the droplet evaporation process. As the droplet evaporates, the velocity inside the droplet decreases, the temperature increases, and the evaporation flux on the surface of the droplet increases. Due to the wedge effect, the evaporation flux at the contact line is small at the initial stage of droplet evaporation, and the evaporation flux reaches the maximum at the point where the wedge effect disappears in the later stage. Environmental factors will also affect droplet evaporation. The increase in relative humidity will inhibit the droplet evaporation, and the increase in ambient temperature will promote the droplet evaporation. The increase of substrate superheat can significantly increase the droplet evaporation rate. The decrease of the initial contact angle and receding contact angle of the droplet will increase the droplet evaporation rate. The effect of Prandtl number on the droplet evaporation is judged by changing the thermal conductivity of the droplet, and it is found that the increase of Prandtl number will slightly reduce the droplet evaporation rate.