Numerical study on surface-heterogeneity-induced anisotropic impact dynamics of droplet

Droplet impact on flat surfaces with heterogeneity is expected to trigger unusual impact dynamics, such as anisotropic spreading and directional rebounding, which in turn could be utilized in the control of droplet motion in many industrial processes. The present work illustrates a numerical study on droplet impact on a flat superhydrophobic substrate coated with a heterogeneous rectangle area, the influence of different positions and wettability of this heterogeneous area on the impact dynamics is investigated. The simulation results show the wettability of the heterogeneous area can impose significant influence on the spreading, retracting, and bouncing processes, especially when the heterogeneous area is located on a site other than the initial contact point, the bouncing of droplet is more likely to happen, and the contact time also becomes shorter. The clear pictures and analysis of the impact dynamics could advance the knowledge of how to control droplet motion by surface coatings.