Numerical Simulation of Leidenfrost Effect of Droplets on Porous Substrate

Abstract The Leidenfrost effect refers to the phenomenon where a liquid droplet instantaneously contacts a high-temperature surface, forming a vapor film that suspends it above the surface. To overcome the increased heat resistance and deteriorated heat transfer caused by the Leidenfrost effect, the surface texturing has been employed to enhance the Leidenfrost point. In this study, a VOF phase-change model coupled with species transport models was established to investigate the phase-change, spreading, and permeation processes of droplet on high-temperature porous surfaces. Furthermore, the effects of heating surface temperature (423 K to 623 K) on droplet dynamics were explored. The results indicate that, due to the competition between capillary forces from the porous structure and vapor expansion, the porous surfaces exhibit a delaying effect on the Leidenfrost phenomenon compared to the flat surfaces. The evaporation of droplets on a porous surface generates higher pressure due to hindered vapor diffusion within the porous structure.