3D lattice Boltzmann simulation of self-propelled single-droplet jumping on microstructured surfaces during condensation

Self-propelled droplet transport on surfaces can re -expose the condensation nucleation sites and is crucial for the enhancement of dropwise condensation heat transfer. In this paper, dropwise condensation and Laplace pressure driven single -droplet jumping on microstructured surfaces are simulated by a three-dimensional non -orthogonal MRT pseudopotential lattice Boltzmann model. The overall process of dropwise condensation on micropillar surfaces, including dewetting transitions and single droplet jumping, is well observed. The simulation results indicate that there is an optimal aspect ratio for the droplet to reach maximum detaching velocity. The energy conversion efficiency from surface energy to kinetic energy reaches -14.2 % when the aspect ratio equals 3.0. Moreover, the effect of microstructure on droplet directional jumping is analyzed. It is demonstrated that the droplet's movement relies on both the direction of the micropillars and the expansion direction of the top liquid sphere due to the pressing effect of the liquid column. To control the jumping direction of the droplet, it is essential to utilize microstructures to regulate the bursting phase of the droplet. Our study illustrates the mechanism of single droplet jumping during condensation and provides guidance for the design of surface structures for the directional transport of condensed droplets.