Bubble capture and migration in Couette-Taylor flow

Bubble capture and migration under the effect of organized structures in we ak turbulent Couette-Taylor flow between two concentric cylinders, the inne r one rotating, has been investigated. Bubbles generated at the free surfac e for large enough angular velocities are sucked into the flow by the upper organized structures. Then they migrate progressively from top to bottom b y jumping from cell to cell. With an upper solid stationary wall instead of the free surface, injected bubbles are trapped by the coherent vortices be yond a critical Taylor number. However, in this situation there is no migra tion mechanism carrying the bubbles from top to bottom. This particular mig ration and capture process, able to act against the forces of buoyancy, has been investigated by perturbing the flow by adding a vertical plate protru ding from the inner surface of the solid stationary wall. The perturbation so introduced causes the deformation of the upper coherent structures and r einstalls the migration of the bubbles.