Numerical simulation of dropwise condensation on rough structures in the presence of non-condensable gas using LBM

Dropwise condensation on rough surfaces enhanced with pillars in the presence of non-condensable gas (NCG) including the initial nucleation process is simulated using the multispecies multiphase lattice Boltzmann method, and the effect of mass fraction of NCG, the surface wettability, the bottom wall temperature and the geometrical parameter (the pillar height H) on condensation process are investigated. It's found that these four factors all have an effect on the nucleation position, waiting time, condensate behaviors, and the wetting state of the droplet. With higher values of NCG mass fraction, surface hydrophobicity, pillar height H, and lower bottom wall temperature, the nucleation occurs on top of the pillars and the waiting time before nucleation gets longer. It's also concluded that the wetting state of the droplet tends to be the Cassie state, and the average heat flux gets smaller with higher values of the former three parameters and lower bottom wall temperature.