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 limited. The azimuthal velocity profiles for the Taylor vortex, wavy vortex, and turbulent Taylor vortex flow in the annulus between a rotating 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 repeated for several Reynolds numbers within each flow regime to study both the spatial dependence and the Reynolds number dependence of the azimuthal velocity. The experimental results for the Taylor vortex flow regime compare well with the Davey perturbation expansion of the Navier-Stokes equations about the circular Couette flow solution [J. Fluid Mech. 14, 336 (1962)]. The measured azimuthal velocity fields also indicate two predominant effects with increasing Reynolds number: the magnitude of the radial gradient of azimuthal velocity near both cylinders increases and the radial outflow region between pairs of vortices becomes increasingly jet-like.