Spatial distribution of heat flux and fluctuations in turbulent Rayleigh-Bénard convection

Lakkaraju, Rajaram; Stevens, Richard J. A. M.; Verzicco, Roberto; Großmann, Siegfried; Prosperetti, Andréa; Sun, Chao; Lohse, Detlef

doi:10.1103/physreve.86.056315

Cited by 22 publications

(14 citation statements)

References 45 publications

(65 reference statements)

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“…Figure 31(b) shows the measured time series of the temperature fluctuation δT (t) (top curve), vertical velocity (middle curve) v z (t), and the instantaneous vertical flux J z (t) (bottom curve) near the sidewall. The local heat flux was measured with very good precision, and the measured results are nicely consistent with the theoretical predictions [5] and recent numerical simulations [121]. Recently, by using commercial heat flux sensors, du Puits et al [122] measured the local heat flux simultaneously at the surfaces of the heating and the cooling plates (see [122] for further details).…”

Section: Global Heat Transport and Local Heat Fluxsupporting

confidence: 74%

Experimental techniques for turbulent Taylor–Couette flow and Rayleigh–Bénard convection

Sun

Zhou

2014

Nonlinearity

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Taylor-Couette (TC) flow and Rayleigh-Bénard (RB) convection are two systems in hydrodynamics, which have been widely used to investigate the primary instabilities, pattern formation, and transitions from laminar to turbulent flow. These two systems are known to have an elegant mathematical similarity. Both TC and RB flows are closed systems, i.e. the total energy dissipation rate exactly follows from the global energy balances. From an experimental point of view, the inherent simple geometry and symmetry in these two systems permits the construction of high precision experimental setups. These systems allow for quantitative measurements of many different variables, and provide a rich source of data to test theories and numerical simulations. We review the various experimental techniques in these two systems in fully developed turbulent states.

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Section: Global Heat Transport and Local Heat Fluxsupporting

confidence: 74%

Experimental techniques for turbulent Taylor–Couette flow and Rayleigh–Bénard convection

Sun

Zhou

2014

Nonlinearity

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“…It was expected that the plume contributions arise mostly from the side walls while the background part is dominantly in the center of the cell. On this basis, predictions for the local convective heat flux J c and the temperature fluctuations T rms were developed and found to be in agreement with laboratory experiments [35,36] and recent direct numerical simulations [37].…”

Section: Scaling Theory By Grossmann and Lohsementioning

confidence: 66%

“…Kraichnan derived the ranges for the Prandtl numbers in (36) and (37) from the ranges that should hold for the thickness scales in his boundary layer models. Interestingly, Nu ∼ Ra 1/2 is a scaling that is derived as a rigorous upper bound to the turbulent heat transport when applying variational calculus to the Boussinseq equations (7) to (9).…”

Section: Kraichnan's Classical Scaling Theorymentioning

confidence: 99%

New perspectives in turbulent Rayleigh-Bénard convection

2012

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Abstract. Recent experimental, numerical and theoretical advances in turbulent Rayleigh-Bénard convection are presented. Particular emphasis is given to the physics and structure of the thermal and velocity boundary layers which play a key role for the better understanding of the turbulent transport of heat and momentum in convection at high and very high Rayleigh numbers. We also discuss important extensions of Rayleigh-Bénard convection such as non-Oberbeck-Boussinesq effects and convection with phase changes.

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“…24 Further studies show that apart from the horizontal plates, the largest heat flux is also located close to but directly at the vertical walls. 26,27 …”

Section: Discussionmentioning

confidence: 98%

Aspect-ratio dependency of Rayleigh-Bénard convection in box-shaped containers

2013

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We report on a numerical study of the aspect-ratio dependency of Rayleigh-Bénard convection, using direct numerical simulations. The investigated domains have equal height and width while the aspect ratio Γ of depth per height is varied between 1/10 and 1. The Rayleigh numbers \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ra}}$\end{document}Ra for this study variate between 105 and 109, while the Prandtl number is \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Pr}} = 0.786$\end{document}Pr=0.786. The main focus of the study concerns the dependency of the Nusselt number \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Nu}}$\end{document}Nu and the Reynolds number \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Re}}$\end{document}Re on \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ra}}$\end{document}Ra and Γ. It turns out that due to Γ, differences to the cubic case (i.e., Γ = 1) in \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Nu}}$\end{document}Nu of up to 55% and in \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Re}}$\end{document}Re of up to 97% occur, which decrease for increasing \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ra}}$\end{document}Ra. In particular for small Γ sudden drops in the \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ra}}$\end{document}Ra-scaling of \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Nu}}$\end{document}Nu and \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Re}}$\end{document}Re appear for \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ra}}\approx 10^6$\end{document}Ra≈106. Further analysis reveals that these correspond to the onset of unsteady motion accompanied by changes in the global flow structure. The latter is investigated by statistical analysis of the heat flux distribution on the bottom and top plates and a decomposition of the instantaneous flow fields into two-dimensional modes. For \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ra}}$\end{document}Ra slightly above the onset of unsteady motion (i.e., \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ra}}\approx 10^6$\end{document}Ra≈106) for all considered Γ ⩽ 1/3 a four-roll structure is present, which corresponds to thermal plumes moving vertically through the domain's center. For \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ra}}\ge 10^7$\end{document}Ra≥107, also for small Γ, a single-roll structure is dominant, in agreement with two-dimensional simulations and experiments at larger \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ra}}$\end{document}Ra and \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Pr}}$\end{document}Pr.

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Spatial distribution of heat flux and fluctuations in turbulent Rayleigh-Bénard convection

Cited by 22 publications

References 45 publications

Experimental techniques for turbulent Taylor–Couette flow and Rayleigh–Bénard convection

Experimental techniques for turbulent Taylor–Couette flow and Rayleigh–Bénard convection

New perspectives in turbulent Rayleigh-Bénard convection

Aspect-ratio dependency of Rayleigh-Bénard convection in box-shaped containers

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