Droplet impact dynamics on Janus-textured heated substrates

Abstract

In this paper, the droplet impact dynamic behavior of droplet on Janus-textured heated substrates is numerically investigate by using the thermal Lattice Boltzmann method. The effect of several factors like the wettability, the Jakob number and the Weber number on the droplet impact dynamic behavior on Janus-textured heated surface are studied in detail. The simulation results show three types of boiling states, i.e., contact boiling, transition boiling and film boiling. The droplets in contact boiling state directionally migrate toward the denser region, while the droplets move toward the sparser region for film boiling state at low Weber number, which agrees with the direction of droplet motion in experiments [Zhang et al., Adv. Funct. Mater., 2019, 29, 1904535]. The self-propelled droplets on the Janus-textured heated substrates is owning to unbalanced Young's fore, vapor pressure difference and thermophoretic force. Moreover, The Janus-textured surface with low wettability has superior nucleation behavior resulting in their typically easy transition from efficient transition boiling state to inefficient film boiling state. In addition, the boiling states of the droplet change from the contact boiling state to the transition boiling state and then to the film boiling state as the Jakob number increases.