Transition to Turbulence in Non-Uniform Counter-Rotating Taylor-Couette Flow
Abstract
The sequence of bifurcations leading to turbulence in a strongly counter-rotating Taylor-Couette system with an ‘hour glass’ shaped inner cylinder is investigated experimentally. This spatial inhomogeneity produces a symmetric ‘hump’ of Reynolds number corresponding to an annulus of supercritical flow at the midspan bounded by regions of stability towards both ends. The study is motivated by the idea that localized instabilities of spatially non-uniform flows are more representative of those found in real imperfect fluid systems. Moreover, the sequence of bifurcations in the present system appears to be clearer than in the standard uniform-gap system where disturbance patterns are strongly affected by end conditions. As the inner cylinder Reynolds number Rei is increased for a high constant negative outer cylinder rotation, the base flow becomes unstable with respect to laminar spiral vortices travelling symmetrically away from the midspan. These two systems of spirals subsequently start to overlap in the midspan region and interact to produce turbulent spots. Increasing Rei further leads to turbulent spiral and chevron structures. A qualitative and quantitative description of the patterns based on the analysis of time series of Kalliroscope reflectivity measurements will be presented, including 1D and 2D spatio-temporal spectra and phase space reconstructions.
- Publication:
-
APS Division of Fluid Dynamics Meeting Abstracts
- Pub Date:
- November 1999
- Bibcode:
- 1999APS..DFD..FL07B