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Symmetric Holmboe instabilities in a laboratory exchange flow

Published online by Cambridge University Press:  25 September 2009

EDMUND W. TEDFORD ,
R. PIETERS  and
G. A. LAWRENCE
EDMUND W. TEDFORD*
Affiliation:
Department of Civil Engineering, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
R. PIETERS
Affiliation:
Department of Civil Engineering, University of British Columbia, Vancouver, BC V6T 1Z4, Canada Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
G. A. LAWRENCE
Affiliation:
Department of Civil Engineering, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
*
†Email address for correspondence: ttedford@eos.ubc.ca
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Abstract

Laboratory experiments have been conducted that test the predictions of Holmboe (Geofys. Publ., vol. 24, 1962, pp. 67–112). Symmetric Holmboe instabilities are observed during steady, maximal two-layer exchange flow in a long laboratory channel of rectangular cross-section. Internal hydraulic controls at each end of the channel isolate the subcritical region within the channel from disturbances in the reservoirs. Inside the channel, the instabilities form cusp-like waves that propagate in both directions. The phase speed of the instabilities is consistent with Holmboe's theory and increases along the length of the channel as a result of the gradual acceleration of each layer. This acceleration causes the wavelength of any given instability to increase in the flow direction until it is approximately twice the most amplified wavelength. At this point new waves develop with the result that the average wavelength is almost constant along the length of the channel.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 636 , 10 October 2009 , pp. 137 - 153
Copyright
Copyright © Cambridge University Press 2009

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