I may never get tired of drone videos of sheep herding. They are mesmerizing to watch and full of so many characteristics of flow. Like a compressible fluid, the herd squeezes together as it passes through a gate, then spreads and decreases density as it reaches the pasture. The sequence of sheep moving down the road reminds me of pipe flow, with a boundary layer of sheep along the edge who choose to graze rather than move with the herd. There are even sheep vortices in this video, folks. Vortices of sheep! How could you resist watching?! (Video credit: L. Patel; via Colossal; submitted by Florian T. and Matevz D.)
Celebrating the physics of all that flows