Collision, coalescence, and breakup of snowflakes in homogeneous and isotropic turbulence

Snowflakes, carried by a strong wind, may collide, coalesce, and/or break up in the air. This process will likely result in a new distribution of snowflake size, a critical piece of information when estimating icing hazards in any field instrument or air vehicle, e.g., wind turbine, aircraft wing. To gain an in-depth understanding of how strong wind may impact such snowflake dynamics, we take the first step to experimentally quantify the collision, coalescence, and breakup of snowflakes in a homogeneous and isotropic (HI) turbulent flow condition. An in-house designed, open-wall turbulence chamber was implemented to generate HI turbulence. It is a one-meter diameter, truncated hexahedron shape, with eight fans at each corner pushing airflow towards the center region of the chamber. We characterize turbulence properties and track the trajectory of each snowflake using high-speed particle imaging/tracking velocimetry at different Taylerscale Reynolds numbers. Artificial snowflakes are used to test the feasibility of using this apparatus in studying snowflake dynamics in HI turbulence.