Bringing in more expertise: Playing with Rolf Käse

Yesterday Torge and I spent a fun Friday night trying out new rotating tank experiments together with Rolf Käse. Rolf taught the lab course that got me into tank experiments (back in 2004!) and he’s still such a huge inspiration!

Rolf brought his tank which features a conical bottom, and this gives so many more options! Which we might or might not include in class at some point 😉

For example we can show planetary Rossby waves by releasing ice cubes when the tank is spun up to solid body rotation. We’ve showed planetary Rossby waves in tanks before, but now we aren’t constrained by boundaries like we were before and the ice cube can just travel around the tank until it has melted completely.

Fish-shaped blue ice cube is melting in a rotating tank of water. Its melt water shows planetary Rossby waves

Or, if we cool right in the center of the tank and then drip dye in, we can see how it spreads over time. Here we see that in the middle, where we’ve just injected some dye, it’s still sinking down in a turbulent 3D fashion. But dye that has been in the tank a little longer has spread along the bottom of the tank in a spiral pattern.

Side view into a rotating tank with a conical bottom with cooling in the middle

Depending on how quickly we turn the tank, that is! Below we are turning faster than above, so here the heat exchanges happens via eddies, not overturning.

Heat exchange happening through eddies in a rotating tank with cooling in the middle

And here is a picture of us. Thanks for a fun tank experiment session, we will have to repeat this very soon! 🙂