Dynamic Behavior of Droplet Impact on Inclined Surfaces with Acoustic Waves

Droplet impact on
arbitrary inclined surfaces is of great interest
for applications such as antifreezing, self-cleaning, and anti-infection.
Research has been focused on texturing the surfaces to alter the contact
time and rebouncing angle upon droplet impact. In this paper, using
propagating surface acoustic waves (SAWs) along the inclined surfaces,
we present a novel technique to modify and control key droplet impact
parameters, such as impact regime, contact time, and rebouncing direction.
A high-fidelity finite volume method was developed to explore the
mechanisms of droplet impact on the inclined surfaces assisted by
SAWs. Numerical results revealed that applying SAWs modifies the energy
budget inside the liquid medium, leading to different impact behaviors.
We then systematically investigated the effects of inclination angle,
droplet impact velocity, SAW propagation direction, and applied SAW
power on the impact dynamics and showed that by using SAWs, droplet
impact on the nontextured hydrophobic and inclined surface is effectively
changed from deposition to complete rebound. Moreover, the maximum
contact time reduction up to ∼50% can be achieved, along with
an alteration of droplet spreading and movement along the inclined
surfaces. Finally, we showed that the rebouncing angle along the inclined
surface could be adjusted within a wide range.