In a return to their roots, this Slow Mo Guys video features paint flowing on (and off!) a spinning disk. To help us see what’s going on, Gav uses a trick that’s familiar to many fluid dynamicists: he rotates the high-speed footage at the same speed that the disk rotates. This transformation places the viewer into a reference frame where the disk appears stationary, so that small changes in the flow are apparent.
It makes for a gorgeous view as centrifugal force flings the paint outward and eventually breaks it into drops. The rotation speed is unfortunately so high that the spinning completely dominates all other forces. The few runs with more viscous acrylic paint show some hints of more interesting behaviors that might be visible with a slower rotation rate (which would make the tug of war between inertia/viscosity/surface tension and centrifugal force less one-sided). Anyone got a high-speed camera, some speed control, and a willingness to get messy? (Image and video credit: The Slow Mo Guys)