Droplet Impact on Dry, Superhydrophobic Surfaces with Micro-scale Roughness Elements

Book excerpt: Most aircraft accidents are caused by technical problems or weather-related issues. One cause of weather-related incidents is in-flight icing, which can induce negative performance characteristics and endanger the operation of an airplane. Various researchers investigating the problem of in-flight icing have proposed ice-phobic coatings as one viable solution. For this purpose, it is critical to study the behavior of a droplet impact on different types of surfaces. As an alternative to physical testing, three-dimensional numerical simulation using computational fluid dynamics offers a promising strategy for evaluating the effects of surface characteristics. Using the volume of fluid method, three simulations of high-speed droplet impact on superhydrophobic surfaces with and without micro-scale roughness elements, were generated. The simulations showed that, for the roughness configurations considered, the superhydrophobic surfaces with micro-scale roughness elements were significantly less effective at repelling the droplet than the smooth superhydrophobic surfaces.