Simulation of the Impact and Solidification of Super Cooled Water Droplets

Book excerpt: In order to study in-flight ice adhesion at the droplet-scale, a strategy is presented to simulate the impact and solidification of a super cooled water droplet on a cooled substrate. Upon impact, nucleation is assumed to occur instantaneously, and properties of the droplet are chosen to account for the nucleation process. Simulations are performed in ANSYS Fluent using a coupled Volume of Fluid and Level-Set method to capture the air-water interface and an Enthalpy-Porosity method to capture the liquid-solid interface. Calibration of a simulation parameter, Amush, is performed in order to match experimental data for different surface types and surface temperatures. The calibrated simulation strategy is applied to low-speed, in-flight icing conditions. The effects of surface variation and droplet diameter variation are investigated, providing insight into the icephobicity of super hydrophobic surfaces. Numerical results suggest that large droplets (approximately 200 micron-diameter) will freeze and adhere to a super hydrophobic surface.