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The flapping shear layer formed by flow separation from the forward corner of a square cylinder

Published online by Cambridge University Press:  26 April 2006

D. A. Lyn  and
W. Rodi
D. A. Lyn
Affiliation:
School of Civil Engineering, Purdue University, W. Lafayette, IN 47907, USA
W. Rodi
Affiliation:
Institute for Hydrodynamics, University of Karlsruhe, D-7500 Karlsruhe, Germany
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Abstract

The turbulent shear layer and the associated recirculation region on the sidewall formed in flow separation from the forward corner of a square cylinder have been studied with one-component laser-Doppler velocimetry. Because of vortex shedding, the flow is approximately periodic, and is treated as a separated flow undergoing largeamplitude forcing at the shedding frequency. Phase (ensemble)-averaged velocities and turbulence intensities were obtained, and a close relationship in phase and amplitude between phase-averaged turbulence intensities and gradients of phase-averaged velocity is found in much of the flow region. The similarity behaviour of the phase-averaged profiles in the shear layer as well as the streamwise growth of the shear layer are investigated. While phase-averaged velocity profiles collapse well in similarity coordinates, normalized turbulence intensities exhibit systematic deviations from similarity. Shear-layer growth also departs markedly from the linear growth law of unforced plane mixing layers. The effect of the recirculation is suggested as a possible explanation for some of these deviations. Similarities to and differences from steady and forced mixing layers, steady separated flows with recirculation, and unsteady boundary layers are discussed.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 267 , 25 May 1994 , pp. 353 - 376
Copyright
© 1994 Cambridge University Press

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