Session AT: Vortex Dynamics and Vortex Flows I
8:00 AM–10:10 AM, Sunday, November 22, 2009
Room: 200H
Chair: Jeffrey Marshall, University of Vermont
Abstract ID: BAPS.2009.DFD.AT.3
Abstract: AT.00003 : Vortex suppression in the wake of counter rotating cylinders
8:26 AM–8:39 AM
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Abstract 
Authors:
Peter Dewey
(Princeton University)
Alexander J. Smits
(Princeton University)
Digital particle image velocimetry is used to study the flow past a pair of counter rotating cylinders placed side-by-side normal to the freestream flow direction. The Reynolds numbers based on cylinder diameter is varied from 100 to 200 and gap-to-diameter ratios of 1, 3 and 5 are considered. An unsteady wake consisting of a pair of von K\'{a}rm\'{a}n vortex streets is present in the flow field when the cylinders are rotated below a critical value. Above this critical value, counter rotation of the cylinders suppresses vortex formation. The critical rotational speed varies only slightly with Reynolds number but exhibits a strong dependence on the gap-to-diameter ratio. As the gap-to-diameter ratio increases, the critical rotational speed approaches values expected to suppress vortex formation for a single rotating cylinder, indicating that the wakes of the cylinder pair have more interaction for small gap-to-diameter ratios. At sufficiently high rotational speeds the streamlines around the cylinder pair resemble a doublet potential flow. The experiments were inspired by the computations performed by Andy Chan and Antony Jameson at Stanford University.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.DFD.AT.3