Droplet impact characteristics on hydrophobic surfaces with partial electrowetting effects

Droplet impact on surfaces integrated with the electrowetting effect has been recently explored to control droplet spreading and recoiling behavior on hydrophobic surfaces. With the integration of electrowetting, the spreading of the impacting droplet on hydrophobic surfaces increases, whereas the rebound tendency is suppressed. The present work numerically investigates the droplet impact on hydrophobic surfaces under partial electrowetting (EW) effects. In partial EW, the electrowetting effect is immediately cut off once the droplet attains the maximum spreading diameter. In addition, based on the energy conservation principle, a mathematical model is developed to predict the maximum spreading diameter of the droplet and its kinetic energy during bouncing for different parameters. The partial EW technique enhances the maximum spreading diameter and reduces the recoiling time compared to full EW and no EW effect. The recoiling time decreases with the increase in voltage amplitude, frequency, Weber number, and surface wettability.