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Shear fronts and an experimental stratified shear flow

Published online by Cambridge University Press:  29 March 2006

A. D. McEwan  and
P. G. Baines
A. D. McEwan
Affiliation:
CSIRO Division of Atmospheric Physics, Station Street, Aspendale, Victoria 3195, Australia
P. G. Baines
Affiliation:
CSIRO Division of Atmospheric Physics, Station Street, Aspendale, Victoria 3195, Australia
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Abstract

The theoretical and experimental evaluation of a laboratory device for creating a controlled shear flow in a continuously stratified liquid is described. The shear is created by the movement of the end barriers of a rectangular channel. If these barriers are impulsively set into uniform shear motion, this motion propagates away in the form of a front of width $O((h/n) (Nt)^{\frac{1}{3}})$ travelling with uniform speed Nh/nπ, where N is the (constant) buoyancy frequency, t is time, n is the vertical modal number and his the channel depth. The shear produced has roughly twice the duration of that attainable using a tilting tube (Thorpe 1968) of similar dimensions. Shear enhancement is possible by introducing a properly designed flow contraction. If N(z) is variable, the shear profile obtained is that appropriate to the lowest internal wave mode of infinite length.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 63 , Issue 2 , 3 April 1974 , pp. 257 - 272
Copyright
© 1974 Cambridge University Press

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