(347h) Ordered Structure Of Interacting Bubbles In A Couette Device With Taylor Vortices

Air bubbles injected to the viscous fluid sheared in a Couette device form a highly ordered structure. In a short time scale, the bubbles are getting entrapped in the secondary rotating flow of the Taylor vortices and are pushed to the center streamline of the vortex defying buoyancy. During a longer time scale the inertial interaction between the bubbles in the primary shear flow drives the bubbles away from each other. Equal size bubbles eventually assume an ordered string with equal separation distances between all neighbors. This phenomenon repeats itself regardless of the number of bubbles in the flow. Hence, doublets will assume opposite positions, triplets will form a triangle, four bubbles will arrange in a square and so on. We present visualizations, measurements and a 2D analysis.