Rotating Convection

Looking inside the water tank

In this experiment, in order to see inside the convection layer, we used 1mm glass sheets for the top and bottom boundary. Glass has better thermal conductivity than water, but not as good as metals, so inevitably a gap in temperature occurred above and below the glass sheets. In this experiment, we estimated the temperature gap on the inner side of the glass in contact with the working fluid to be half the temperature gap between the hot and cold water.

 

Wipers

In a water tank constructed like a set of nested boxes, if bubbles attach to the surface of the glass they can be difficult to get rid of. With the method we selected for making the fluid movement visible, we had to look at the weak light of scattered liquid crystal capsules, but any bubbles, even ones not in line with the light plane, light up quite brightly. In order to remove the bubbles, we sunk a sponge attached to the length of an aluminium rod in each layer and used it whenever bubbles occurred.