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Intrusive gravity currents between two stably stratified fluids

Published online by Cambridge University Press:  18 March 2010

BENJAMIN D. MAURER ,
DIOGO T. BOLSTER  and
P. F. LINDEN
BENJAMIN D. MAURER
Affiliation:
Scripps Institution of Oceanography, La Jolla, CA 92093-0208, USA
DIOGO T. BOLSTER
Affiliation:
Department of Civil Engineering and Geological Sciences, University of Notre Dame, IN 46556, USA
P. F. LINDEN*
Affiliation:
Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093-0411, USA
*
†Email address for correspondence: pflinden@ucsd.edu
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Abstract

We present an experimental and numerical study of one stratified fluid propagating into another. The two fluids are initially at rest in a horizontal channel and are separated by a vertical gate which is removed to start the flow. We consider the case in which the two fluids have the same mean densities but have different, constant, non-zero buoyancy frequencies. In this case the fluid with the smaller buoyancy frequency flows into the other fluid along the mid-depth of the channel in the form of an intrusion and two counter-flowing gravity currents of the fluid with the larger buoyancy frequency flow along the top and bottom boundaries of the channel. Working from the available potential energy of the system and measurements of the intrusion thickness, we develop an energy model to describe the speed of the intrusion in terms of the ratio of the two buoyancy frequencies. We examine the role of the stratification within the intrusion and the two gravity currents, and show that this stratification plays an important role in the internal structure of the flow, but has only a secondary effect on the speeds of the exchange flows.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 647: Dedicated to Professor S. H. Davis on his 70th birthday , 25 March 2010 , pp. 53 - 69
Copyright
Copyright © Cambridge University Press 2010

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References

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