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Unsteady nearshore natural convection induced by constant isothermal surface heating

Published online by Cambridge University Press:  20 July 2012

Yadan Mao ,
Chengwang Lei  and
John C. Patterson
Yadan Mao*
Affiliation:
State Key Laboratory of Geological Processes and Mineral Resources, Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan, Hubei 430074, China
Chengwang Lei
Affiliation:
School of Civil Engineering, The University of Sydney, NSW 2006, Australia
John C. Patterson
Affiliation:
School of Civil Engineering, The University of Sydney, NSW 2006, Australia
*
†Email address for correspondence: yadan_mao@cug.edu.cn
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Abstract

The present investigation is concerned with natural convection in a wedge-shaped domain induced by constant isothermal heating at the water surface. Complementary to the study of daytime heating by solar radiation relevant to nearshore regions of lakes and reservoirs previously reported by the same authors, this study focuses on sensible heating imposed by the atmosphere when it is warmer than the water body. A semi-analytical approach coupled with scaling analysis and numerical simulation is adopted to resolve the problem. Two flow regimes are identified depending on the comparison between the Rayleigh number and the inverse of the square of the bottom slope. For the lower Rayleigh number regime, the entire flow domain eventually becomes isothermal and stationary. For the higher Rayleigh number regime, the flow domain is composed of two distinct subregions, a conductive subregion near the shore and a convective subregion offshore. Within the conductive subregion, the maximum local flow velocity occurs when the thermal boundary layer reaches the local bottom, and the subregion eventually becomes isothermal and stationary. In the offshore convective subregion, a steady state is reached with a distinct thermal boundary layer below the surface and a steady flow velocity. The dividing position between the two subregions and the major time and velocity scales governing the flow development in both subregions are proposed by the scaling analysis and validated by corresponding numerical simulation.

JFM classification

Convection: Buoyant boundary layers Geophysical and Geological Flows: Gravity currents Geophysical and Geological Flows: Topographic effects
Type
Papers
Information
Journal of Fluid Mechanics , Volume 707 , 25 September 2012 , pp. 342 - 368
Copyright
Copyright © Cambridge University Press 2012

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