ARTICLE:

• RAYLEIGH-BENARD CONVECTION IN A PERFECTLY CONDUCTING CUBICAL CAVITY AT Pr=0.7  download article

J. Pallares
Department of Mechanical Engineering, University Rovira i Virgili, Avinguda dels Països Catalans 26, 43007, Tarragona, Spain

I. Cuesta
Department of Mechanical Engineering, University Rovira i Virgili, Avinguda dels Països Catalans 26, 43007, Tarragona, Spain

Francesc Xavier Grau
Department of Mechanical Engineering, University Rovira i Virgili, Av. Paisos Catalans 26, 43007 Tarragona, Catalonia, Spain

ABSTRACT

This paper discusses flow structures and heat transfer rates generated by Rayleigh-Benard convective motions of a Boussinesq fluid (Pr=0.7) in a perfectly conducting cubical cavity. Direct numerical simulations were conducted in the laminar regime (7×10³< Ra ≤ 10⁵) and the large-eddy simulation (LES) technique was used for the simulations at two high Rayleigh numbers (Ra=10 and Ra=10⁸) Computations were carried out using a second-order accuracy finite volume code with a dynamic localized one-equation subgrid scale (SGS) model with constant SGS Prandtl number. Two single roll structures and a four-roll structure in which the axis of each roll is perpendicular to one sidewall were found to be stable in the laminar regime. At high Rayleigh numbers, instantaneous flow visualizations and the three-dimensional topology of the time-averaged flow reveal that the mean flow structure can be understood as the superposition of two four-roll structures with their rolls rotating in opposite directions.

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