Spherical Couette flow with superimposed throughflow
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This work deals with the generalization of the spherical Couette flow from a closed flow into an open flow system. A superimposed throughflow in meridional direction leads to novel flow structures and stability behaviour. A analytical solution for the superposition of the spherical Couette and the source-sink flow is given for the creeping flow. Numerical simulations for steady and time-dependent rotationally symmetric solutions are presented for a large Reynolds number range. These solutions represents the non-uniqueness of the supercritical spherical Couette flows. Their symmetry with respect to the equator and time-behaviour depends strongly on the throughflow Reynolds number. The experiments show the rich variety of supercritical solutions depending on the rotation and throughflow parameters. Rotationally symmetric vortices and spiral vortices are realized in steady and time-dependent form. For the pure source-sink flow the instabilities are formed like banana shaped structures. The existence regions and transitions between the different modes of flow are presented in maps. For the rotationally symmetric states there is a good agreement between theory and experiments.
KeywordsReynolds Number Meridional Plane Meridional Direction Taylor Number Taylor Vortex
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