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Influence of global rotation and Reynolds number on the large-scale features of Taylor–Couette flow

[ mercredi 29-09-2010 19:00 | anglais ]Influence of global rotation and Reynolds number on the large-scale features of Taylor–Couette flow René Delfos Laboratory for Aero and Hydrodynamics, JMBurgerscentre for Fluid Mechanics,
Delft University of Technology,
the Netherlands

Résumé :
We experimentally study the flow between two coaxial and independently rotating cylinders. We determined the scaling of the torque with Reynolds number (Re) and ‘angular mean velocity ratio’ or Rotation number (Re). With stereoscopic Particle Image Velocimetry, we analyse the mean velocity profiles at a fairly high Reynolds number, and we show the peculiar role of perfect counter-rotation for the emergence of organized large scale secondary flow structures in the mean part of this very turbulent flow. We show that these ‘turbulent Taylor vortices’ appear in a smooth and continuous way: the transition resembles a supercritical bifurcation of the secondary mean flow.