Splashing behavior of impacting droplets on grooved superhydrophobic surfaces

During water droplet impingement onto a rice-leaf-inspired grooved superhydrophobic surface, the unidirectional textures can reduce the solid–liquid contact time through modifying the droplet impact dynamics. The influence of the groove geometry on the splashing of impacting droplets is still unrevealed. In this study, we experimentally identify the droplet bouncing and splashing regimes on grooved superhydrophobic surfaces of varying parameters. Asymmetric spreading and retracting of droplets are observed on the surfaces, accompanied by obvious liquid jets generated within the grooves. As the impact velocity increases, secondary droplets are ejected from the rim of the liquid jets, which is the onset of droplet splashing on the grooved superhydrophobic surfaces. We find that the critical Weber number for the splash of liquid jets decreases with the groove width but increases with the droplet diameter. Scaling analysis is performed to model the splashing criteria and explain its dependence on groove parameters and droplet properties. This research advances the understanding of droplet splashing dynamics on textured superhydrophobic surfaces, which is promising for some agricultural and industrial applications.