A numerical simulation of a droplet impacting a small superhydrophobic cylinder eccentrically

Droplet collisions on superhydrophobic cylindrical surfaces are widely seen in industrial applications. To investigate their dynamic behavior, numerical simulations of droplets impacting eccentrically on the surface of a small superhydrophobic cylinder are performed in this work. The eccentricity e ranges from 0 to 1.2 mm, and the impact velocity ranges from 0.5 to 2 m/s. The effects of the impact velocity and eccentricity are studied in detail. The results show that increasing the eccentricity e reduces the maximum spreading factor and exacerbates the asymmetry of droplets in the azimuthal direction. When the droplets impact on the small cylindrical surface, two collision modes are observed: an asymmetric stretching regime and a stretched rebound regime. The formulation (Wecr/D∗=230ε+31) is employed as a criterion to distinguish between the two modes. With increasing eccentricity e, an asymmetrical flow of droplets from the non-impact side to the impact side occurs, accompanied by a transition in the dynamic behavior of the droplets from stretching to bouncing. The asymmetrical stretching and stretched rebound can effectively decrease the contact time between the droplet and the cylindrical surface, resulting in a reduction of up to 32% during eccentric impact.