Routes to chaos in wide-gap spherical Couette flow

The dynamical behavior of wide-gap instabilities in spherical Couette how i s investigated experimentally with chaos analyzing techniques applied on ti me series from Laser-Doppler-Velocimetry (LDV) measurements. With an increa sing Reynolds number of the rotating inner sphere, the flow undergoes two H opf 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 coordi nate. The transition processes are accompanied by phenomena such as a locke d torus in reconstructed phase space and periodic long wave modulations of chaotic flows. Although the investigated gap widths are all classified as w ide, a comparison exhibits significant differences in the development of ch aotic motion. (C) 1999 American Institute of Physics. [S1070-6631(99)00506- 1].