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ISSN Online: 2377-424X

ISBN Print: 0-85295-345-3

International Heat Transfer Conference 10
August, 14-18, 1994, Brighton, UK

ON THE EFFECT OF PRANDTL NUMBER AND ASPECT RATIO UPON LAMINAR NATURAL-CONVECTION FLOWS IN VERTICAL CHANNELS

Get access (open in a dialog) DOI: 10.1615/IHTC10.3280
pages 483-488

Résumé

Numerical solutions of the full elliptic Navier-Stokes and energy equations have been obtained to study the flow in a vertical channel for a wide range of Rayleigh and Prandtl numbers. The influence of the channel aspect ratio, b/Lc, which appears as an independent parameter in the elliptic formulation, on the average Nusselt number is analyzed. The ranges of parameters that transform the elliptic model into a parabolic model are investigated in detail. The average Nusselt number is found to be almost independent of the channel aspect ratio for the whole range of the modified Rayleigh number (b/L c) Ra, except for low enough Rayleigh numbers, for which the influence of the counterflow heat conduction at the entrance of the channels is evaluated. Correlations are proposed giving the average Nusselt number as a function of (b/Lc)Ra for different Prandtl numbers. In the single-plate boundary-layer limit, these correlations are in good agreement with some available results; however, it has been found that the fully-developed limit, also included in the correlations, is only actually reached under certain circumstances.