Effect Of Pillared Surfaces With Different Shape Parameters On Droplet Wettability Via Lattice Boltzmann Method

In this study, to explore the influences of different pillar shape parameters on the wettability of a water droplet, a two-dimensional pseudopotential model at a large density ratio was established to predict the wettability of a pillared wall microstructure via lattice Boltzmann method. The improved force term and tunable surface tension term were implemented in the model. The formation of vortex was studied during droplet contacts the surface. The influences of different pillar heights, widths, and spacings on the wettability and wettability conversion of droplets were investigated. The results reveal that the vortexes will be generated during droplet contacts the surface. The pillars can hold up droplets, thereby greatly increasing the droplet contact angle. With the increase of the pillar height, the droplet gradually shifts from filling the convex gap to being held up by the air in the gap. The pillar width mainly determines contact angle. Moreover, the contact angle decreases with the increase of the pillar spacing. However, when the pillar spacing is large enough, the droplet can enter the gap closest to the droplet. As roughness increases, the water droplet is converted from Wenzel state to Cassie state.