Droplet impact on cylindrical surfaces: Effects of surface wettability, initial impact velocity, and cylinder size

Abstract

HypothesisDroplet impact on cylindrical surfaces is a widespread phenomenon observed in both nature and industrial applications. The wettability and size of the cylinders, and the initial impact velocity, are expected to influence the impact dynamics, such as generating different droplet morphology, spreading/retracting processes, and contact time, which could finally determine the anti-icing property of power transmission lines. ExperimentsA particle-based mesh-free numerical approach, many-body dissipative particle dynamics, is employed to study the impact dynamics. The cylinders with three different sizes and three types of wettability are modelled, and different initial impact velocities are set. FindingsThe simulations show the two liquid films (or lamellae) formed after impact can coalesce at the bottom site of a hydrophilic cylinder while they keep separate on hydrophobic and superhydrophobic cylinders. The maximum spreading diameter in the axial direction increases with the increase of impact velocity and cylinder size. Besides, the distribution of droplet detachment mode shows a strong dependence on initial impact velocity and cylinder size. In bouncing mode, the contact time increases with the increase of impact velocity while in dripping/bouncing mode, it has an opposite trend. The splashing angle is also observed to be dependent on the cylinder size.