Characteristic of droplet oscillation on the surface of rectangular hydrophobic grooves

Droplet oscillation is an important phenomenon in nature, it has important scientific research value. Since the liquid droplet behavior when impinging on the hydrophobic plate surface with grooved texture is obviously different from that on the smooth plate surface, the characteristics of the oscillation of the height and the contact line of water droplet on the rectangular hydrophobic grooves are studied via high-speed camera. Due to the anisotropic wetting of the rectangular hydrophobic grooves, the length of the contact line of water droplet in the parallel direction of the groove is longer than that in the vertical direction. However, it does not affect the period of the attenuation oscillation in the height direction, which means the droplet oscillation period has no relationship with the width of the slot. What's more, due to the binding effect of the barrier on the surface within hydrophobic grooves, the spreading and retraction of the contact line do not follow the typical damping oscillation law. It stabilizes rapidly after several oscillations. For example, when the velocity of water droplet is 0.61m/s, the contact line is stable after 2 oscillations, but the water droplet is still oscillating. In addition, we give the reason why the water droplet oscillation period is irrelevant to the groove size.