Temperature fluctuations relevant to thermal-plume dynamics in turbulent rotating Rayleigh-Bénard convection

2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Shan-Shan Ding ◽  
Hui-Min Li ◽  
Wen-Dan Yan ◽  
Jin-Qiang Zhong
Keyword(s):  
Temperature Fluctuations ◽  
Thermal Plume ◽  
Plume Dynamics ◽  
Bénard Convection ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

Reynolds number scaling in cryogenic turbulent Rayleigh–Bénard convection in a cylindrical aspect ratio one cell

2017 ◽  
Vol 832 ◽  
pp. 721-744 ◽  
Author(s):  
Věra Musilová ◽  
Tomáš Králík ◽  
Marco La Mantia ◽  
Michal Macek ◽  
Pavel Urban ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Large Scale ◽  
Temperature Fluctuations ◽  
Reynolds Numbers ◽  
Distribution Functions ◽  
Bénard Convection ◽  
Benard Convection ◽  
Helium Gas ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

We perform an experimental study of turbulent Rayleigh–Bénard convection up to very high Rayleigh number, $10^{8}<Ra<10^{14}$, in a cylindrical aspect ratio one cell, 30 cm in height, filled with cryogenic helium gas. We monitor temperature fluctuations in the convective flow with four small (0.2 mm) sensors positioned in pairs 1.5 cm from the sidewalls and 2.5 cm vertically apart and symmetrically around the mid-height of the cell. Based on one-point and two-point correlations of the temperature fluctuations, we determine different types of Reynolds numbers, $\mathit{Re}$, associated with the large-scale circulation (LSC). We observe a transition between two types of $\mathit{Re}(\mathit{Ra})$ scaling around $\mathit{Ra}=10^{10}{-}10^{11}$, which is accompanied by a scaling change of the skewness of the probability distribution functions (PDFs) of the temperature fluctuations. The $\mathit{Re}(\mathit{Ra})$ dependencies measured near the sidewall at Prandtl number $\mathit{Pr}\sim 1$ are consistent with the $\mathit{Ra}^{4/9}\mathit{Pr}^{-2/3}$ scaling above the transition, while for $\mathit{Ra}<10^{10}$, the $\mathit{Re}(\mathit{Ra})$ dependencies are steeper. It seems likely that this change in $\mathit{Re}(\mathit{Ra})$ scaling is linked to the previously reported change in the Nusselt number $\mathit{Nu}(\mathit{Ra})$ scaling. This behaviour is in agreement with independent cryogenic laboratory experiments with $\mathit{Pr}\sim 1$, but markedly different from the $\mathit{Re}$ scaling obtained in water experiments ($\mathit{Pr}\sim 3.3{-}5.6$). We discuss the results in comparison with different versions of the Grossmann–Lohse theory.

Test of the anomalous scaling of passive temperature fluctuations in turbulent Rayleigh–Bénard convection with spatial inhomogeneity

2014 ◽  
Vol 753 ◽  
pp. 104-130 ◽  
Author(s):  
Xiaozhou He ◽  
Xiao-dong Shang ◽  
Penger Tong
Keyword(s):  
Structure Function ◽  
Temperature Fluctuations ◽  
Thermal Dissipation ◽  
Temperature Structure ◽  
Anomalous Scaling ◽  
Bénard Convection ◽  
Benard Convection ◽  
Turbulent Statistics ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

AbstractThe scaling properties of the temperature structure function (SF) and temperature–velocity cross-structure function (CSF) are investigated in turbulent Rayleigh–Bénard convection (RBC). The measured SFs and CSFs exhibit good scaling in space and time and the resulting SF and CSF exponents are obtained both at the centre of the convection cell and near the sidewall. A universal relationship between the CSF exponent and the thermal dissipation exponent is found, confirming that the anomalous scaling of passive temperature fluctuations in turbulent RBC is indeed caused by the spatial intermittency of the thermal dissipation field. It is also found that the difference in the functional form of the measured SF and CSF exponents at the two different locations in the cell is caused by the change of the geometry of the most dissipative structures in the (inhomogeneous) temperature field from being sheetlike at the cell centre to filament-like near the sidewall. The experiment thus provides direct evidence showing that the universality features of turbulent cascade are linked to the degree of anisotropy and inhomogeneity of turbulent statistics.

scholarly journals Statistics of velocity and temperature fluctuations in two-dimensional Rayleigh-Bénard convection

2017 ◽  
Vol 96 (2) ◽  
Author(s):  
Yang Zhang ◽  
Yong-Xiang Huang ◽  
Nan Jiang ◽  
Yu-Lu Liu ◽  
Zhi-Ming Lu ◽  
...  
Keyword(s):  
Temperature Fluctuations ◽  
Two Dimensional ◽  
Bénard Convection ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

Turbulent temperature fluctuations in a closed Rayleigh–Bénard convection cell

2019 ◽  
Vol 874 ◽  
pp. 263-284 ◽  
Author(s):  
Yin Wang ◽  
Xiaozhou He ◽  
Penger Tong
Keyword(s):  
Temperature Fluctuations ◽  
Convection Cell ◽  
Thermal Plumes ◽  
Bénard Convection ◽  
Conducting Plate ◽  
Benard Convection ◽  
Analytic Expressions ◽  
Spatio Temporal ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

We report a systematic study of spatial variations of the probability density function (PDF) $P(\unicode[STIX]{x1D6FF}T)$ for temperature fluctuations $\unicode[STIX]{x1D6FF}T$ in turbulent Rayleigh–Bénard convection along the central axis of two different convection cells. One of the convection cells is a vertical thin disk and the other is an upright cylinder of aspect ratio unity. By changing the distance $z$ away from the bottom conducting plate, we find the functional form of the measured $P(\unicode[STIX]{x1D6FF}T)$ in both cells evolves continuously with distinct changes in four different flow regions, namely, the thermal boundary layer, mixing zone, turbulent bulk region and cell centre. By assuming temperature fluctuations in different flow regions are all made from two independent sources, namely, a homogeneous (turbulent) background which obeys Gaussian statistics and non-uniform thermal plumes with an exponential distribution, we obtain the analytic expressions of $P(\unicode[STIX]{x1D6FF}T)$ in four different flow regions, which are found to be in good agreement with the experimental results. Our work thus provides a unique theoretical framework with a common set of parameters to quantitatively describe the effect of turbulent background, thermal plumes and their spatio-temporal intermittency on the temperature PDF $P(\unicode[STIX]{x1D6FF}T)$.

Plume dynamics in rotating Rayleigh–Bénard convection

2016 ◽  
Vol 380 (14-15) ◽  
pp. 1363-1367 ◽  
Author(s):  
Alexandre B. Pieri ◽  
Fabrizio Falasca ◽  
Jost von Hardenberg ◽  
Antonello Provenzale
Keyword(s):  
Plume Dynamics ◽  
Bénard Convection ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard
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