Numerical analysis of droplet impact and heat transfer on an inclined wet surface

A numerical model based on the coupled level set and volume of fraction (CLSVOF) method is developed to investigate the dynamics and heat transfer of a droplet impacting on an inclined wet surface. Numerical results show that the droplet shows spreading, edge jets and splashing upon impact with high velocities. The front spreading factor and liquid velocity are larger than the back-spreading ones. As the impact velocity increases, both the front and back spreading factors and velocities increase. Significant air entrapment is observed when the droplet approaches the liquid film on the solid surface. The pressure difference between the trapped air and the liquids leads to the formation of an air film underneath the droplet. The entrapped air also shows a dynamic process. It becomes a small bubble at the initial stage of droplet impact and reduces heat transfer from the liquid droplet to the surface. This effect diminishes when the trapped air escapes the liquids. The average wall heat flux is found to be closely correlated to the impact velocity, but that correlation weakens as the impact velocity increases. Results from this study provide better understandings of the fluid dynamics and heat transfer during droplet oblique impact on inclined wet surfaces.