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Double-diffusive plumes in unconfined and confined environments

Published online by Cambridge University Press:  20 April 2006

Trevor J. McDougall
Trevor J. McDougall
Affiliation:
Research School of Earth Sciences, Australian National University, GPO Box 4, Canberra, A.C.T. Present address: Division of Oceanography, CSIRO, GPO Box 1538, Hobart, Tas. 7001. Australia.
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Abstract

We address two aspects of the influence of double diffusion on convection from point buoyancy sources (plumes). First we consider double-diffusive convection acting in conjunction with buoyancy from an isolated source in an unconfined environment, and we study the problem of when fluxes of properties occur in the opposite direction to that of the initial buoyancy. A simple dimensional analysis is in good agreement with the experimental data for these ‘counterbuoyant’ fluxes of properties. Secondly, we consider a double-diffusive plume discharging into a confined environment. The plume now does not always reach the bottom (or top) of the confined environment, but can spread out into the environment at intermediate depths. Double-diffusive interfaces form, and we describe their development and the evolution of the density profile in the confined environment. A quantitative measure of the importance of double-diffusive convection in relation to the normal filling-box mechanism is obtained in the experiments by using the measured density profile, and this correlates well with a theoretically derived parameter Bρ.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 133 , August 1983 , pp. 321 - 343
Copyright
© 1983 Cambridge University Press

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