Dynamic simulation of droplet impacting on superhydrophobic surface with cubic protrusion

Abstract

Droplet impact dynamics on a superhydrophobic surface with a cubic protrusion was simulated by the lattice Boltzmann method and the contact time reduction mechanism due to the fact that the cubic protrusion was explored. In addition, the droplet bouncing behavior was analyzed with the effect of a wide range of Weber numbers (18.28–106.77). The simulated results showed three distinct bouncing modes, which are bouncing with no ring formation, bouncing with ring formation and disappearance, and bouncing with ring formation. The contact time can be sharply reduced by up to 58.41% as the We number exceeds the critical value 67.16, which is induced by the liquid ring bouncing generated by the collision between the inner and outer rims. In addition, no effect can be seen during the spreading stage, and hence, the liquid ring punctured by the cubic protrusion mainly reduces the retraction time of the droplet impact process. Moreover, the retraction distance can be shortened with the increase in We. Symmetrical dynamics during spreading and retraction due to the cubic protrusion can be seen, which is different from the asymmetric behavior on a macroridge. Discussions on the instantaneous velocity field further support the reduction mechanism of the contact time.