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Turbulence structure near a sharp density interface

Published online by Cambridge University Press:  21 April 2006

Imad A. Hannoun ,
Harindra J. S. Fernando  and
E. John List
Imad A. Hannoun
Affiliation:
Jaycor, PO Box 85154, San Diego, CA 92138-9259, USA
Harindra J. S. Fernando
Affiliation:
Mechanical and Aerospace Engineering, Arizona State University, Tempe, AZ 85287, USA
E. John List
Affiliation:
W. M. Keck Laboratory of Hydraulics and Water Resources, California Institute of Technology, Pasadena, CA 91125, USA
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Abstract

The effects of a sharp density interface and a rigid flat plate on oscillating-grid induced shear-free turbulence were investigated experimentally. A two-component laser-Doppler velocimeter was used to measure turbulence intensities in and above the density interface (with matched refractive indices) and near the rigid flat plate. Energy spectra, velocity correlations, and kinetic energy fluxes were also measured. Amplification of the horizontal turbulent velocity, coupled with a sharp reduction in the vertical turbulent velocity, was observed near both the density interface and the flat plate. These findings are in agreement with some previous results pertaining to shear-free turbulence near rigid walls (Hunt & Graham 1978) and near density interfaces (Long 1978). The results imply that, near the density interface, the turbulent kinetic energy in the vertical velocity component is only a small fraction of the total turbulent kinetic energy and indicate that the effects of the anisotropy created by the density interface or the flat plate are confined to the large turbulence scales.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 189 , April 1988 , pp. 189 - 209
Copyright
© 1988 Cambridge University Press

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