Contact time of droplet impact against an inclined hydrophobic surface.

This work presents a study of a droplet impacting an inclined hydrophobic surface using lattice Boltzmann method (LBM) simulation. The influence of surface inclination, surface wettability, and the Weber number on the dynamic of spreading and receding is elucidated. Intriguingly, the contact time is independent of the surface inclination. The surface wettability and Weber number do not affect the spreading time, while they significantly influence the receding dynamic. To further quantitatively describe the influence of surface wettability and Weber number, scaling laws of the receding rate are established as Vret ∼ (1 − cos θ)−0.25 and Vret ∼ Wen0.19, and, thus, scaling laws of the receding time are established as tr ∼ (1 − cos θ)−0.5 and tr ∼ Wen0.1, respectively, where Wen is the normal Weber numbers and θ is the contact angle. Based on this, a relationship of the contact time for a droplet impacting an inclined hydrophobic surface is ultimately established as tc = 3.1(ρR03/σ)1/2 (1 − cos θ)−1/2Wen0.1, where ρ, R0, and σ denote the droplet density, radius, and surface tension, respectively. This study provides a quantitative relationship to calculate the contact time of a droplet impacting an inclined hydrophobic surface, which can simultaneously efficiently evaluate the anti-freezing, anti-icing, and self-cleaning performance of hydrophobic surfaces employed in practical applications. [ABSTRACT FROM AUTHOR]