Droplet rebound on nonwetting surfaces is a common phenomenon. However, the underlying physics regulating the contact time remains unclear. In this work, we investigate droplet impacts on superamphiphobic surfaces through experiments and theoretical analyses. By analyzing the spreading and retraction of droplet impinging processes over a wide range of Weber numbers ($We$), it is revealed that droplet impacts experience three regimes as $We$ is varied, which are denoted as the Hertz collision ($We<1$), transition ($1<We<10$), and oscillation ($We>10$) regimes. In the Hertz collision regime, the droplet impinging process is temporally symmetric, i.e., the spreading time, $t_S$, and the retraction time, $t_R$, are almost the same. Furthermore, $t_S$ and $t_R$ decrease with increasing $We$ and follow a power-law dependence, which is different from previous theories. In the transition regime, $t_S$ remains dominated by the Hertz collision, while $t_R$ is governed by droplet oscillation. In the oscillation regime, $t_S$, $t_R$, and the total contact time, $t_C$, become independent of $We$. These three regimes are valid for both monophase and compound droplets. The findings in this work advance the understanding and offer a clear picture of droplet impact dynamics.

Close

PrevNext

View figure in article

• Drop & bubble phenomena
• Drop interactions
• Drops & bubbles