Velocity Distribution and Velocity Fluctuation in the Laminar-Turbulent Transition of Spherical Couette Flow.

Abstract

The velocity distributions and fluctuating velocities in the laminar-turbulent transition of spherical Couette flow with only the inner sphere rotating, have been experimentally studied at two meridian angles, θ=60°and 90°, for the case of clearance ratio 0.14. The distributions of azimuthal and meridian velocity components have been considered over a wide range of Reynolds number. Logarithmic laws were obtained on the azimuthal velocity profiles in the turbulent boundary layer near the outer sphere wall for θ=60°and 90°. The phases of fluctuating velocity advance radially from the outer sphere to the inner sphere at θ=90°, but they depend on the type of disturbances at θ=60°. The phase-averaged fluctuating velocity profile in the presence of spiral TG (Taylor-Gortler) vortices differs from that in the presence of traveling azimuthal waves. Amplitude of fluctuation becomes large in the gap a little toward the outer sphere wall in the presence of spiral TG vortices at θ=60°, but a little toward the inner sphere wall in the presence of traveling azimuthal wave at θ=90°.