Laminar and turbulent Rayleigh–Bénard convection in a perfectly conducting cubical cavity

✍ Scribed by J. Pallares; I. Cuesta; F.X. Grau

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 942 KB
• Volume: 23
• Category: Article
• ISSN: 0142-727X
• DOI: 10.1016/s0142-727x(02)00182-0

✦ Synopsis

This paper discusses flow structures and heat transfer rates generated by Rayleigh-B e enard convective motions of a Boussinesq fluid with a Prandtl number of 0.7 in a perfectly conducting cubical cavity. Complete numerical simulations of laminar flows were conducted in the range of Rayleigh numbers 7 Â 10 3 6 Ra 6 10 5 . The large-eddy simulation (LES) technique was used for the simulations at two high Rayleigh numbers (Ra ¼ 10 6 and 10 8 ). LES were carried out using a second-order accurate finite volume code with a dynamic localized one-equation subgrid-scale (SGS) model with constant SGS Prandtl number. In the laminar regime, 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. LES of Rayleigh-B e enard convection in an infinite fluid layer were initially carried out and results were seen to be in agreement with direct numerical simulations (DNS) reported in the literature. At Ra ¼ 10 6 and 10 8 , the instantaneous velocity and temperature fields present strong fluctuations with respect to the time-averaged flow field. The confining effect of the conductive lateral walls of the cavity generates, in the unsteady flows at Ra ¼ 10 6 and 10 8 , persistent vertical currents near these walls. The recirculation of these ascending and descending flows towards the central region of the cavity produces large-scale organized rolling motions, which imprint the topology of the time-averaged flow field in form of two vortex ring structures located near the horizontal walls.