Droplet behavior analysis on inclined, highly sticky, or slippery superhydrophobic nanostructured surfaces by observation and SPH simulation

Although the motion of water droplets on a superhydrophobic surface is important for industrial pro-cesses, the characteristics of the slippery/sticky contact line are not fully understood at the macroscopic continuum fluid scale. In this study, we tracked the dynamic contact angle of the solid-liquid-gas phase when droplets moved on a superhydrophobic nanostructured surface. High-speed observations revealed the pinning/unpinning behavior of the droplets' receding contact part.The droplets were modeled by introducing momentum attenuation as a friction model in the smoothed particle hydrodynamics (SPH) framework, which assumes a macroscopically smooth surface with different slippery properties. From a macroscopic perspective, droplet pinning requires both horizontal movement and the suppression of the rotational motion acting on the solid-liquid interface. A sticky solid surface was successfully modeled using this simple model; thus, it can be applied to more practical problems such as prediction of the motion of melts on coke. (c) 2021 Elsevier Ltd. All rights reserved.