Routes to chaos in wide-gap spherical Couette flow

The dynamical behavior of wide-gap instabilities in spherical Couette how is investigated experimentally with chaos analyzing techniques applied on time series from Laser-Doppler-Velocimetry (LDV) measurements. With an increasing Reynolds number of the rotating inner sphere, the flow undergoes two Hopf bifurcations and several mode changes. The transition scenarios for two different gap widths investigated can be described primarily as the Ruelle-Takens-Newhouse type and show a strong dependence on the meridional coordinate. The transition processes are accompanied by phenomena such as a locked torus in reconstructed phase space and periodic long wave modulations of chaotic flows. Although the investigated gap widths are all classified as wide, a comparison exhibits significant differences in the development of chaotic motion. (C) 1999 American Institute of Physics. [S1070-6631(99)00506-1].