Aerodynamic characteristics of water droplets on superhydrophobic surfaces

Abstract

The primary objective of this study is to examine droplet dynamics on superhydrophobic surfaces in order to develop strategies to reduce droplet adhesion. The investigation utilized computational fluid dynamics simulations, employing the unsteady Reynolds-averaged Navier–Stokes equations in conjunction with the volume of fluid method. The central focus of this study pertains to the behavior of two droplets on a substrate characterized by a contact angle of 155° within a two-dimensional computational domain. The parametric studies include analyzing the dynamics of droplets with different freestream velocities, droplet sizes, distances between droplets, and the order in which droplets are arranged. Several key findings emerge from this study, notably the observation of an attractive force between two droplets prior to their coalescence. An attraction force between two water droplets was seen in many cases examined due to flow separation, where negative pressure gradients and recirculation flows affected the droplet farthest from the inlet moving upstream. Additional droplet dynamics include the detachment of droplets from the superhydrophobic substrate, the vorticity development after the droplets, and the subsequent wall forces influenced by parametric studies. These findings highlight the inherent capabilities of treated substrates, including self-cleaning attributes, hydrophobicity, and reduced friction. The potential applications based on this research can influence diverse fields, notably materials science, medicine, and engineering.