Investigation of droplet evaporation on heterogeneous surfaces using a three-dimensional thermal multiphase lattice Boltzmann model

Abstract

In this paper, a three-dimensional thermal multiphase lattice Boltzmann (LB) model is established to simulate droplet evaporation on heterogeneous surfaces, which employs an improved three-dimensional pseudopotential multiphase LB model and a finite-difference scheme to simulate the fluid flow and the temperature field, respectively. First, the thermal multiphase LB model is numerically validated with the D2 law. Subsequently, the model is applied to simulate droplet evaporation on chemically ring-patterned surfaces. The stick-slip-jump behavior of evaporating droplets on chemically ring-patterned surfaces confirms the pinning-depinning mechanism proposed based on two-dimensional analyses. Furthermore, the dynamics of droplet evaporation on chemically stripe-patterned surfaces is investigated. Numerical results show that the droplet evaporates in a stick-slip-jump fashion in the direction perpendicular to the stripes. It is observed that the lifetime of the slip state on chemically stripe-patterned surfaces is significantly reduced in comparison with that on chemically ring-patterned surfaces, which is found to arise from the influence of the contact line on the hydrophobic stripes. In addition, it is shown that in the direction parallel to the stripes the droplet evaporates in the constant contact angle (CCA) mode. The contact radius in the parallel direction gradually decreases with time, but increases when a jump occurs in the perpendicular direction, owing to the rapid retraction of the droplet in the perpendicular direction during the jump.