Dynamics of Snowflakes Impacting Superhydrophobic Surfaces

Snow and ice accumulation on surfaces presents significant safety and efficiency challenges across various industries, necessitating the development of effective mitigation strategies. In this study, the dynamics and energy dissipation of natural snowflakes impacting superhydrophobic surfaces (SHS) were explored using high-speed imaging and a novel image processing method. The size, velocity (impact and bounce), and contact time of natural wet snowflakes were quantitatively analyzed, identifying two primary impact outcomes: bouncing and fragmentation. The analysis focused on bouncing to study the coefficient of restitution (COR) of snowflakes. It was found that small snowflakes (<1.40 mm in diameter) with low impact velocities (<2.90 m/s) tend to be bounced, whereas larger, faster snowflakes are more likely to be fragmented. For the first time, the contact time of natural snowflakes on SHS was also reported, introducing a dimensionless contact time (DCT) for quantifying energy dissipation during the impact. The results indicate that energy dissipation has a cubic relationship with snowflake size and a quadratic relationship with its impact velocity, demonstrating that larger and faster snowflakes dissipate more energy. It is observed that a reduction in DCT leads to an exponential increase in COR and a decrease in normalized energy dissipation, supporting the theoretical prediction that the COR approaches one and the normalized energy dissipation approaches zero as the DCT approaches zero. These results are significant for enhancing the design and efficiency of anti-icing surfaces, contributing to the development of models that simulate snow accumulation behaviors and inform better design of both active and passive snow mitigation strategies.