AZIMUTHAL VELOCITY IN SUPERCRITICAL CIRCULAR COUETTE-FLOW

Although the stability of supercritical circular Couette flow has been studied extensively, results for the velocity field of the flow are l imited. The azimuthal velocity profiles for the Taylor vortex, wavy vo rtex, and turbulent Taylor vortex flow in the annulus between a rotati ng inner cylinder and a fixed outer cylinder with fixed end conditions were measured using laser Doppler velocimetry. The azimuthal velocity was measured at about 300 points per vortex pair, distributed in both the radial and axial directions. This measurement procedure was repea ted for several Reynolds numbers within each flow regime to study both the spatial dependence and the Reynolds number dependence of the azim uthal velocity. The experimental results for the Taylor vortex flow re gime compare well with the Davey perturbation expansion of the Navier- Stokes equations about the circular Couette flow solution [J. Fluid Me ch. 14,336 (1962)]. The measured azimuthal velocity fields also indica te two predominant effects with increasing Reynolds number: the magnit ude of the radial gradient of azimuthal velocity near both cylinders i ncreases and the radial outflow region between pairs of vortices becom es increasingly jet-like.