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Unsteady near-shore natural convection induced by surface cooling

Published online by Cambridge University Press:  04 December 2009

YADAN MAO ,
CHENGWANG LEI  and
JOHN C. PATTERSON
YADAN MAO*
Affiliation:
School of Engineering and Physical Sciences, James Cook University, Townsville QLD 4811, Australia
CHENGWANG LEI
Affiliation:
School of Engineering and Physical Sciences, James Cook University, Townsville QLD 4811, Australia
JOHN C. PATTERSON
Affiliation:
School of Engineering and Physical Sciences, James Cook University, Townsville QLD 4811, Australia
*
†Email address for correspondence: [email protected]
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Abstract

Natural convection in calm near-shore waters induced by daytime heating or nighttime cooling plays a significant role in cross-shore exchanges with significant biological and environmental implications. Having previously reported an improved scaling analysis on the daytime radiation-induced natural convection, the authors present in this paper a detailed scaling analysis quantifying the flow properties at varying offshore distances induced by nighttime surface cooling. Two critical functions of offshore distance have been derived to identify the distinctness and the stability of the thermal boundary layer. Two flow scenarios are possible depending on the bottom slope. For the relatively large slope scenario, three flow regimes are possible, which are discussed in detail. For each flow regime, all the possible distinctive subregions are identified. Two different sets of scaling incorporating the offshore-distance dependency have been derived for the conduction-dominated region and stable-convection-dominated region respectively. It is found that the scaling for flow in the stable-convection-dominated region also applies to the time-averaged mean flow in the unstable region. The present scaling results are verified by numerical simulations.

JFM classification

Boundary Layers: Boundary Layers Geophysical and Geological Flows: Gravity currents
Type
Papers
Information
Journal of Fluid Mechanics , Volume 642 , 10 January 2010 , pp. 213 - 233
Copyright
Copyright © Cambridge University Press 2009

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Footnotes

‡

Present address: School of Civil Engineering, The University of Sydney, NSW 2006, Australia

§

Present address: School of Civil Engineering, The University of Sydney, NSW 2006, Australia

References

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