Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-28T05:23:56.838Z Has data issue: false hasContentIssue false
  • English
  • Français

Experimental study of high-Rayleigh-number convection in a horizontal cavity with different end temperatures

Published online by Cambridge University Press:  20 April 2006

Adrian Bejan ,
Adnan A. Al-Homoud  and
Jorg Imberger
Adrian Bejan
Affiliation:
Department of Mechanical Engineering, University of Colorado, Boulder, Colorado, USA
Adnan A. Al-Homoud
Affiliation:
Department of Mechanical Engineering, University of Colorado, Boulder, Colorado, USA
Jorg Imberger
Affiliation:
Department of Civil Engineering, University of Western Australia, Nedlands, Australia
Get access Rights & Permissions [Opens in a new window]

Abstract

The paper summarizes results from an experimental study of buoyancy-induced motion and heat transfer in a horizontal rectangular cavity with the two vertical ends at different temperatures and the long horizontal walls adiabatic. The cavity height/length ratio is A = 0·0625. The high-Rayleigh-number range reported on in this paper, 2 × 108 < Ra < 2 × 109, has not been studied before. It is shown that, contrary to lower-Rayleigh-number behaviour known previously, the core flow structure is non-parallel and is dominated by horizontal intrusions flowing along each of the two insulated horizontal walls of the enclosure. The fluid embraced by the two horizontal jets is practically stagnant and thermally stratified. Flow visualization experiments suggest that adjacent to the two horizontal jets two secondary flat cells are formed by the baroclinic pressure field in an analogous way to what is observed in intrusions in a stratified fluid. Nusselt-number-Rayleigh-number results for the overall end-to-end heat transfer in the horizontal direction are reported and compared with previous experimental and theoretical results available for lower Rayleigh numbers. It is shown also that the transition from a parallel core structure to one dominated by intrusion layers is governed by the parameter Ra½A, with Ra¼A < 1 as necessary condition for a parallel core flow.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 109 , August 1981 , pp. 283 - 299
Copyright
© 1981 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

Al-Homoud, A. A. & Bejan, A. 1979 Experimental study of high Rayleigh number convection in horizontal cavity with different end temperatures. Dept Mechanical Engng, Univ. Colorado, Boulder, Rep. CUMER-79–1.Google Scholar
Batchelor, G. K. 1954 Heat transfer by free convection across a closed cavity between vertical boundaries at different temperatures. Quart. J. Appl. Math. 12, 209.Google Scholar
Bejan, A. 1979 Note on Gill's solution for free convection in a vertical enclosure. J. Fluid Mech. 90, 561.Google Scholar
Bejan, A. 1980 A synthesis of analytical results for natural convection heat transfer across rectangular enclosures. Int. J. Heat Mass Transfer 23, 723.Google Scholar
Bejan, A. & Tien, C. L. 1978 Laminar natural convection heat transfer in a horizontal cavity with different end temperatures. J. Heat Transfer 100, 641.Google Scholar
Boyack, B. E. & Kearney, D. W. 1972 Heat transfer by laminar natural convection in low aspect ratio cavities. A.S.M.E. Paper no. 72-HT-2.Google Scholar
Braun, W. H., Ostrach, S. & Heighway, J. E. 1961 Free-convection similarity flows about two dimensional and axisymmetric bodies with closed lower ends. Int. J. Heat Mass Transfer 2, 121.Google Scholar
Cormack, D. E., Leal, L. G. & Imberger, J. 1974 Natural convection in a shallow cavity with differentially heated end walls. Part 1. Asymptotic theory. J. Fluid Mech. 65, 209.Google Scholar
Cormack, D. E., Leal, L. G. & Seinfeld, J. H. 1974 Natural convection in a shallow cavity with differentially heated end walls. Part 2. Numerical solutions. J. Fluid Mech. 65, 231.Google Scholar
Eckert, E. R. G. & Carlson, W. O. 1961 Natural convection in an air layer enclosed between two vertical plates with different temperatures. Int. J. Heat Mass Transfer 2, 106.Google Scholar
Elder, J. W. 1965 Laminar free convection in a vertical slot. J. Fluid Mech. 23, 77.Google Scholar
Gill, A. E. 1966 The boundary layer regime for convection in a rectangular cavity. J. Fluid Mech. 26, 515.Google Scholar
Imberger, J. 1974 Natural convection in a shallow cavity with differentially heated end walls. Part 3. Experimental results. J. Fluid Mech. 65, 246.Google Scholar
Imberger, J., Thompson, R. & Fandry, C. 1976 Selective withdrawal from a finite rectangular tank. J. Fluid Mech. 78, 489.Google Scholar
Koh, R. C. Y. 1976 Buoyancy gravitational spreading. Proc. 15th Coastal Engng Conf. Honolulu.
Kumar, A. & Ostrach, S. 1977 An experimental investigation of natural convection flows in rectangular enclosures of aspect ratios less than unity. Case Western Reserve Univ., Dept Mechanical Aerospace Engng Rep. FTAS/TR-77–132.Google Scholar
Loka, R. R. 1979 Natural convection flows in low aspect ratio rectangular enclosures. M.S. thesis, Dept Mechanical & Aerospace Engng, Case Western Reserve University.
Ostrach, S. 1972 Natural convection in enclosures. Adv. Heat Transfer 8, 161.Google Scholar
Ostrach, S., Loka, R. R. & Kumar, A. 1980 Natural convection in low aspect ratio rectangular enclosures. Paper presented at the 19th Nat. Heat Transfer Conf., Orlando. Florida.
Sernas, V. & Lee, E. I. 1978 Heat transfer in air enclosures of aspect ratio less than one. A.S.M.E. Paper no. 78—WA/HT—7.Google Scholar
Tseng, W. F. 1979 Numerical experiments on free convection in a tilted rectangular enclosure of aspect ratio 05. M.S. thesis, Dept Mechanical & Industrial Engng, Clarkson College, Potsdam, N.Y. (Rep. no. MIE—050.)