Large-scale flow properties of turbulent thermal convection

Ciliberto, S.; Cioni, S.; Laroche, C.

doi:10.1103/physreve.54.r5901

Cited by 150 publications

(127 citation statements)

References 13 publications

Supporting

Mentioning

114

Contrasting

Order By: Relevance

“…Convection of heat occurs primarily as a result of the emission of volumes of hot fluid known as "plumes" from a bottom thermal boundary layer that rise due to a buoyant force, while cold plumes emitted from a top boundary layer sink. In the turbulent regime of Γ = 1 samples that we studied, these plumes drive a large-scale circulation (LSC) [4,5,6,7,8,9,10,11] which is oriented nearly vertically with up-flow and down-flow on opposite sides of the sample.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Earth’s Coriolis force on the large-scale circulation of turbulent Rayleigh-Bénard convection

Brown

Ahlers

2006

Physics of Fluids

View full text Add to dashboard Cite

We present measurements of the large-scale circulation (LSC) of turbulent Rayleigh-Bénard convection in water-filled cylindrical samples of heights equal to their diameters. The orientation of the LSC had an irregular time dependence, but revealed a net azimuthal rotation with an average period of about 3 days for Rayleigh numbers R > ∼ 10 10 . On average there was also a tendency for the LSC to be aligned with upflow to the west and downflow to the east, even after physically rotating the apparatus in the laboratory through various angles. Both of these phenomena could be explained as a result of the coupling of the Earth's Coriolis force to the LSC. The rate of azimuthal rotation could be calculated from a model of diffusive LSC orientation meandering with a potential barrier due to the Coriolis force. The model and the data revealed an additional contribution to the potential barrier that could be attributed to the cooling system of the sample top which dominated the preferred orientation of the LSC at high R. The tendency for the LSC to be in a preferred orientation due to the Coriolis force could be cancelled by a slight tilt of the apparatus relative to gravity, although this tilt affected other aspects of the LSC that the Coriolis force did not.

show abstract

Section: Introductionmentioning

confidence: 99%

Effect of the Earth’s Coriolis force on the large-scale circulation of turbulent Rayleigh-Bénard convection

Brown

Ahlers

2006

Physics of Fluids

View full text Add to dashboard Cite

show abstract

“…They usually embrace the entire convective boundary layer (of the order of 1-3 km in height) and include pronounced convergence flow patterns close to the surface. In the sheared convective flows, the structures represent largescale rolls (cloud streets) stretched along the mean wind [1,2,12] Coherent structures in convective turbulent flows were comprehensively studied theoretically, experimentally and in numerical simulations [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28]. However, some aspects related to the origin of large-scale coherent structures in non-rotating turbulent convection are not completely understood.…”

Section: Introductionmentioning

confidence: 99%

Large-scale instabilities in a nonrotating turbulent convection

2006

View full text Add to dashboard Cite

A theoretical approach proposed in Phys. Rev. E 66, 066305 (2002) is developed further to investigate formation of large-scale coherent structures in a non-rotating turbulent convection via excitation of a large-scale instability. In particular, the convective-wind instability that causes formation of large-scale coherent motions in the form of cells, can be excited in a shear-free regime. It was shown that the redistribution of the turbulent heat flux due to non-uniform large-scale motions plays a crucial role in the formation of the coherent large-scale structures in the turbulent convection. The modification of the turbulent heat flux results in strong reduction of the critical Rayleigh number (based on the eddy viscosity and turbulent temperature diffusivity) required for the excitation of the convective-wind instability. The large-scale convective-shear instability that results in the formation of the large-scale coherent motions in the form of rolls stretched along imposed large-scale velocity, can be excited in the sheared turbulent convection. This instability causes the generation of convective-shear waves propagating perpendicular to the convective rolls. The mean-field equations which describe the convective-wind and convective-shear instabilities, are solved numerically. We determine the key parameters that affect formation of the large-scale coherent structures in the turbulent convection. In particular, the degree of thermal anisotropy and the lateral background heat flux strongly modify the growth rates of the large-scale convective-shear instability, the frequencies of the generated convective-shear waves and change the thresholds required for the excitation of the large-scale instabilities. This study elucidates the origins of the large-scale circulations and rolls in the atmospheric convective boundary layers and the meso-granular structures in the solar convection.

show abstract

“…The experiments are done in cylindrical containers with an aspect ratio Γ ≡ D/L ≈ 1 (L is the height and D is the diameter of the sample). In the turbulent regime of Γ = 1 samples, the plumes drive a large-scale circulation (LSC), also known as the "mean wind", which is oriented nearly vertically with up-flow and down-flow on opposite sides of the sample [4,5,6,7,8,9,10,11].…”

Section: Introductionmentioning

confidence: 99%

“…The dynamics of the LSC include oscillations [6,7,8,12,13,14,15,16,17,18,19] in which the orientation of the upper half of the LSC oscillates out of phase with the lower half [9,20].…”

Section: Introductionmentioning

confidence: 99%

A model of diffusion in a potential well for the dynamics of the large-scale circulation in turbulent Rayleigh–Bénard convection

2008

View full text Add to dashboard Cite

Experimental measurements of properties of the large-scale circulation (LSC) in turbulent convection of a fluid heated from below in a cylindrical container of aspect ratio one are presented and used to test a model of diffusion in a potential well for the LSC. The model consists of a pair of stochastic ordinary differential equations motivated by the Navier-Stokes equations. The two coupled equations are for the azimuthal orientation θ 0 , and for the azimuthal temperature amplitude δ at the horizontal midplane. The dynamics is due to the driving by Gaussian distributed white noise that is introduced to represent the action of the small-scale turbulent fluctuations on the large-scale flow. Measurements of the diffusivities that determine the noise intensities are reported. Two time scales predicted by the model are found to be within a factor of two or so of corresponding experimental measurements. A scaling relationship predicted by the model between δ and the Reynolds number is confirmed by measurements over a large experimental parameter range. The Gaussian peaks of probability distributions p(δ) and p(θ 0 ) are accurately described by the model; however the non-Gaussian tails of p(δ) are not. The frequency, angular change, and amplitude bahavior during cessations are accurately described by the model when the tails of the probability distribution of δ are used as experimental input.

show abstract

Large-scale flow properties of turbulent thermal convection

Cited by 150 publications

References 13 publications

Effect of the Earth’s Coriolis force on the large-scale circulation of turbulent Rayleigh-Bénard convection

Effect of the Earth’s Coriolis force on the large-scale circulation of turbulent Rayleigh-Bénard convection

Large-scale instabilities in a nonrotating turbulent convection

A model of diffusion in a potential well for the dynamics of the large-scale circulation in turbulent Rayleigh–Bénard convection

Contact Info

Product

Resources

About