Hostname: page-component-8448b6f56d-c47g7 Total loading time: 0 Render date: 2024-04-23T21:02:49.294Z Has data issue: false hasContentIssue false

Mixing in internally heated natural convection flow and scaling for a quasi-steady boundary layer

Published online by Cambridge University Press:  17 December 2014

Tae Hattori*
Affiliation:
School of Civil Engineering, The University of Sydney, Sydney, NSW 2006, Australia
John C. Patterson
Affiliation:
School of Civil Engineering, The University of Sydney, Sydney, NSW 2006, Australia
Chengwang Lei
Affiliation:
School of Civil Engineering, The University of Sydney, Sydney, NSW 2006, Australia
*
Email address for correspondence: tae.hattori@sydney.edu.au

Abstract

This study considers the natural convection flow in a water body subjected to heating by solar radiation. The investigation into this type of natural convection flow has been motivated by the fact that it is known to play a crucial role in the daytime heat and mass transfer in shallow regions of natural water reservoirs and lakes, with a resultant impact on biological activity. An analytical solution for temperature in such an internally heated system shows that the temperature stratification consists of an upper stable stratification and a lower unstable stratification. One of the important consequences of such a nonlinear temperature stratification is the limitation of the mixing driven by rising thermal plumes with the penetration length scale of the plumes determining the lower mixed layer thickness. A theoretical analysis conducted in the present study suggests that in relatively deep waters, the lower mixed layer thickness is equal to the attenuation length of the radiation, which has important implications for water quality, including the transport of pollutants and nutrients in the water body. Scalings are also obtained for the quasi-steady boundary layer. The theoretical analysis is validated against numerical simulations.

Type
Papers
Copyright
© 2014 Cambridge University Press 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Adams, E. E. & Wells, S. A. 1984 Field measurements on side arms of lake. J. Hydraul. Engng 110 (6), 773993.Google Scholar
Amati, G., Koal, K., Massaioli, F., Sreenivasan, K. R. & Verzicco, R. 2005 Turbulent thermal convection at high Rayleigh numbers for a Boussinesq fluid of constant Prandtl number. Phys. Fluids 17 (12), 121701.Google Scholar
Armfield, S. W. 1994 Ellipticity, accuracy, and convergence of the discrete Navier–Stokes equations. J. Comput. Phys. 114 (2), 176184.Google Scholar
Armfield, S. W. & Street, R. 2002 An analysis and comparison of the time accuracy of fractional-step methods for the Navier–Stokes equations on staggered grids. Intl J. Numer. Meth. Fluids 38 (3), 255282.Google Scholar
Bednarz, T. P., Lei, C. & Patterson, J. C. 2008 An experimental study of unsteady natural convection in a reservoir model cooled from the water surface. Exp. Therm. Fluid Sci. 32 (3), 844856.Google Scholar
Castaing, B., Gunaratne, G., Heslot, F., Kadanoff, L., Libchaber, A., Thomae, S., Wu, X.-Z., Zaleski, S. & Zanetti, G. 1989 Scaling of hard thermal turbulence in Rayleigh–Benard convection. J. Fluid Mech. 204, 130.CrossRefGoogle Scholar
Coates, M. J. & Patterson, J. C. 1993 Unsteady natural convection in a cavity with non-uniform absorption of radiation. J. Fluid Mech. 256, 133161.Google Scholar
Farrow, D. E. & Patterson, J. C. 1993 On the stability of the near shore waters of a lake when subject to solar heating. Intl J. Heat Mass Transfer 36 (1), 89100.CrossRefGoogle Scholar
Farrow, D. E. & Patterson, J. C. 1994 The daytime circulation and temperature structure in a reservoir sidearm. Intl J. Heat Mass Transfer 37 (13), 19571968.CrossRefGoogle Scholar
Hattori, T., Patterson, J. C. & Lei, C. 2014 Transport and mixing mechanisms in littoral waters induced by absorption of radiation. In Proceedings of the 15th International Heat Transfer Conference, Kyoto, August 10–15.Google Scholar
Hattori, T., Patterson, J. C. & Lei, C. 2015a Scaling and direct stability analyses of natural convection induced by absorption of solar radiation in a parallelpiped cavity. Intl J. Therm. Sci. 88, 1932.CrossRefGoogle Scholar
Hattori, T., Patterson, J. C. & Lei, C. 2015b On the stability of internally heated natural convection due to the absorption of radiation in a laterally confined fluid layer with a horizontal throughflow. Intl J. Heat Mass Transfer 81, 846861.CrossRefGoogle Scholar
Howard, L. N.1966 Convection at high Rayleigh number. Applied Mechanics, Proceedings of the 11th Congress of Applied Mechanics, Munich, Germany, pp. 1109–1115.Google Scholar
Kirk, J. T. O. 1986 Optical limnology – a manifesto. In Limnology in Australia (ed. De Deckker, P. & Williams, W. D.), pp. 3362. CSIRO and Dr W. Junk.CrossRefGoogle Scholar
Kirk, J. T. O. 1994 Light and Photosynthesis in Aquatic Ecosystems. Cambridge University Press.CrossRefGoogle Scholar
Lei, C. & Patterson, J. C. 2002 a Natural convection in a reservoir sidearm subject to solar radiation: experimental observations. Exp. Fluids 32 (5), 590599.CrossRefGoogle Scholar
Lei, C. & Patterson, J. C. 2002 b Unsteady natural convection in a triangular enclosure induced by absorption of radiation. J. Fluid Mech. 460, 181209.Google Scholar
Lei, C. & Patterson, J. C. 2003 A direct stability analysis of a radiation-induced natural convection boundary layer in a shallow wedge. J. Fluid Mech. 480, 161184.Google Scholar
Lei, C. & Patterson, J. C. 2005 Unsteady natural convection in a triangular enclosure induced by surface cooling. Intl J. Heat Fluid Flow 26 (2), 307321.Google Scholar
Leonard, B. P. & Mokhtari, S. 1990 Beyond first-order upwinding: the ultra-sharp alternative for non-oscillatory steady-state simulation of convection. Intl J. Numer. Meth. Engng 30 (4), 729766.CrossRefGoogle Scholar
Malkus, W. V. R. 1954 The heat transport and spectrum of thermal turbulence. Proc. R. Soc. Lond. A 225 (1161), 196212.Google Scholar
Mao, Y., Lei, C. & Patterson, J. C. 2009 Unsteady natural convection in a triangular enclosure induced by absorption of radiation – a revisit by improved scaling analysis. J. Fluid Mech. 622, 75102.CrossRefGoogle Scholar
Maxworthy, T. 1997 Convection into domains with open boundaries. Annu. Rev. Fluid Mech. 29 (1), 327371.CrossRefGoogle Scholar
Monismith, S. G., Imberger, J. & Morison, M. L. 1990 Convective motions in the sidearm of a small reservoir. Limnol. Oceanogr. 35, 16761702.CrossRefGoogle Scholar
Morton, B. R. 1967 Entrainment models for laminar jets, plumes, and wakes. Phys. Fluids 10 (10), 21202127.CrossRefGoogle Scholar
Nicolas, X., Luijkx, J. M. & Platten, J. K. 2000 Linear stability of mixed convection flows in horizontal rectangular channels of finite transversal extension heated from below. Intl J. Heat Mass Transfer 43, 589610.Google Scholar
Norris, S. E.2000 A parallel Navier–Stokes solver for natural convection and free surface flow. PhD thesis, The University of Sydney, Sydney.Google Scholar
Priestley, C. H. B. 1954 Convection from a large horizontal surface. Austral. J. Phys. 7 (1), 176201.Google Scholar
Sparrow, E. M., Goldstein, R. J. & Jonsson, V. K. 1964 Thermal instability in a horizontal fluid layer: effect of boundary conditions and non-linear temperature profile. J. Fluid Mech. 18, 513528.Google Scholar
Stone, H. L. 1968 Iterative solution of implicit approximations of multidimensional partial differential equations. SIAM J. Numer. Anal. 5 (3), 530558.Google Scholar
van der Vorst, H. A. 1981 Iterative solution methods for certain sparse linear systems with a non-symmetric matrix arising from PDE-problems. J. Comput. Phys. 44, 119.Google Scholar
Wirtz, R. A. & Chiu, C. M. 1974 Laminar thermal plume rise in a thermally stratified environment. Intl J. Heat Mass Transfer 17, 323329.Google Scholar