Aspect ratio dependence of heat transfer and large-scale flow in turbulent convection

Jorge Bailon-Cuba; Mohammad S. Emran; Joerg Schumacher

doi:10.1017/S0022112010000820

paper

Aspect ratio dependence of heat transfer and large-scale flow in turbulent convection

arXiv:1002.2908 · doi:10.1017/S0022112010000820

Abstract

The heat transport and corresponding changes in the large-scale circulation (LSC) in turbulent Rayleigh-Bénard convection are studied by means of three-dimensional direct numerical simulations as a function of the aspect ratio $Γ$ of a closed cylindrical cell and the Rayleigh number $R a$ . For small and moderate aspect ratios, the global heat transfer law $N u = A \times R a^{β}$ shows a power law dependence of both fit coefficients $A$ and $β$ on the aspect ratio. A minimum Nusselt number coincides with the point where the LSC undergoes a transition from a single-roll to a double-roll pattern. With increasing aspect ratio, we detect complex multi-roll LSC configurations. The aspect ratio dependence of the turbulent heat transfer for small and moderate $Γ$ is in line with a varying amount of energy contained in the LSC, as quantified by the Proper Orthogonal Decomposition analysis. For $Γ ≳ 8$ the heat transfer becomes independent of the aspect ratio.

17 pages, 11 Postscript figures (in parts downscaled), accepted for J. Fluid Mech

Aspect ratio dependence of heat transfer and large-scale flow in turbulent convection

Abstract

References in corpus (6)

Cited by in corpus (44)