Fig. 3
![Fig. 3](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs40645-015-0058-1/MediaObjects/40645_2015_58_Fig3_HTML.gif)
Schematic and photos of the 3 m experiment. Left: a schematic of the experimental apparatus. Photos, clockwise from top center: the outer sphere; the inner sphere with shaft and lid; the inner sphere being lowered into the outer vessel, which is filled with water in this view; the bottom bearing and rotating fluid junction (allowing heating oil to be circulated in the jacket around the outer sphere)