TRANSITION TO TURBULENCE AND RELAMINARIZATION PHENOMENA IN THE FLOW BETWEEN TWO ROTATING SPHERES

Modes selection of different instabilities that lead to turbulence between two concentric spheres, the inner rotating while the outer is at rest, is investigated through visualization and polarography method. The exploration of the flow regimes was carried out for a dimensionless gap width delta=(R-2-R-1)/R-1 of 0.107, an aspect ratio Gamma=H/d in the interval (17; 21) and a Taylor number in the interval (22; 1500). The influence of these parameters on the appearance of instabilities is elucidated. The evolution of the flow patterns is visualized and quantified by the wall velocity gradients and their fluctuations. The case considered here is closely related to the polarographic method in a spherical shell. At our best knowledge, this has not been studied to the present day.