Icephobic performance of superhydrophobic coatings: A numerical analysis

Understanding the mechanism of cloud-sized particles impact and freezing is crucial to find viable solutions to prevent ice accumulation on critical aerodynamic surfaces such as aircraft wing or nacelle. It has been reported that superhydrophobic surfaces (SHS) have promising anti-icing properties due to their excellent water-repellent characteristics. However, due to the complexity of the freezing phenomenon on superhydrophobic surfaces, the anti-icing performance of such surfaces has not been fully understood. A multi-region multiphase flow solver including phase change has been developed to model the icing of a micro-droplet as it impinges on a superhydrophobic substrate with a given thickness, texture, and solid material thermal properties. The Navier-Stokes equation expressing the flow distribution of the liquid and the gas, coupled with the volume of fluid (VOF) method for tracking the liquid-gas and liquid solid interfaces, was solved numerically using the finite volume methodology. The superhydrophobic morphology is modeled through a series of micro-structured arrays with squared cross-sectional pillars. As such, the thermal contact resistance is inherently accounted by the inclusion of air pockets underneath the micro-droplet. Consequently, the direct effect of surface topology and thermal properties on droplet maximum spreading diameter, penetration to the surface asperities, contact time, and the freezing onset have been investigated. Finally, icephobicity of two similar SHSs with various thermal properties were compared. (C) 2019 Elsevier Ltd. All rights reserved.