Use high-speed footage of water vs. oil flowing through a clear pipe to show how the "edges" of the fluid slow down compared to the center.
The Visual Flow: Why Fluid Mechanics Videos are Essential for Mastering the Subject fluid mechanics videos
It is the single best demonstration of laminar vs. turbulent flow. You will literally see a thin line of dye turn into chaotic swirls as the flow velocity increases. Use high-speed footage of water vs