End effects on the transition to time-dependent motion in the Taylor experiment

Abstract

Laser-Doppler velocimetry has been used to measure the critical Reynolds number for the onset of time-dependent motion and its characteristic features in Taylor-Couette flow. For moderate values of the aspect ratio Γ the critical Reynolds number is observed to be extremely sensitive to length effects, and the form of oscillation arising at the stability limit is found to change in neighboring ranges of Γ. At even higher Reynolds number the oscillation type may change and hysteresis phenomena are observed. These new features are beyond the reach of any available theory and they highlight the need for caution when transition to turbulence observations are interpreted.