| Characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh-Bénard convection |
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| 引用本文： | 方明卫,何建超,胡战超,包芸. Characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh-Bénard convection[J]. 中国物理 B, 2022, 31(1): 14701-014701. DOI: 10.1088/1674-1056/ac012f |
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| 作者姓名： | 方明卫 何建超 胡战超 包芸 |
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| 作者单位： | School of Aeronautics and Astronautics, Sun Yat-sen University, Guangzhou 510275, China |
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| 基金项目： | the National Natural Science Foundation of China(Grant No.11772362);the Shenzhen Fundamental Research Program(Grant No.JCYJ20190807160413162);the Fundamental Research Funds for the Central Universities,Sun Yat-sen University,China(Grant No.19lgzd15). |
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| 摘 要： | We study the characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh–Benard convection in′a square cavity by direct numerical simulations.The Rayleigh number range is 1×108≤Ra≤1×1013,and the Prandtl number is selected as Pr=0.7 and Pr=4.3.It is found that the temperature fluctuation profiles with respect to Ra exhibit two different distribution patterns.In the thermal boundary layer,the normalized fluctuationθrms/θrms,max is independent of Ra and a power law relation is identified,i.e.,θrms/θrms,max～(z/δ)0.99±0.01,where z/δis a dimensionless distance to the boundary(δis the thickness of thermal boundary layer).Out of the boundary layer,when Ra≤5×109,the profiles ofθrms/θrms,max descend,then ascend,and finally drop dramatically as z/δincreases.While for Ra≥1×1010,the profiles continuously decrease and finally overlap with each other.The two different characteristics of temperature fluctuations are closely related to the formation of stable large-scale circulations and corner rolls.Besides,there is a critical value of Ra indicating the transition,beyond which the fluctuation hθrmsiV has a power law dependence on Ra,given by hθrmsiV～Ra?0.14±0.01.
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| 关 键 词： | Rayleigh-Benard temperature fluctuation distribution patterns critical value |
| 收稿时间： | 2021-03-11 |
Characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh-Bénard convection |
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| Ming-Wei Fang,Jian-Chao He,Zhan-Chao Hu,Yun Bao. Characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh-Bénard convection[J]. Chinese Physics B, 2022, 31(1): 14701-014701. DOI: 10.1088/1674-1056/ac012f |
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| Authors: | Ming-Wei Fang Jian-Chao He Zhan-Chao Hu Yun Bao |
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| Affiliation: | School of Aeronautics and Astronautics, Sun Yat-sen University, Guangzhou 510275, China |
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| Abstract: | We study the characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh-Bénard convection in a square cavity by direct numerical simulations. The Rayleigh number range is ${1times }{{10}}^{{8}}le Rale 1times {{10}}^{{13}}$, and the Prandtl number is selected as $Pr=0.7$ and $Pr=4.3$. It is found that the temperature fluctuation profiles with respect to Ra exhibit two different distribution patterns. In the thermal boundary layer, the normalized fluctuation $theta_{rm rms}/theta_{rm rms,max}$ is independent of Ra and a power law relation is identified, $i.e.$, $theta _{rm rms}/theta_{rm rms,max}sim left( z / delta right)^{0.99pm 0.01}$, where $z / delta $ is a dimensionless distance to the boundary ($delta $ is the thickness of thermal boundary layer). Out of the boundary layer, when $Rale 5times {10}^{9}$, the profiles of $theta _{rm rms}/theta_{rm rms,max}$ descend, then ascend, and finally drop dramatically as $z / delta $ increases. While for $Rage 1times {10}^{10}$, the profiles continuously decrease and finally overlap with each other. The two different characteristics of temperature fluctuations are closely related to the formation of stable large-scale circulations and corner rolls. Besides, there is a critical value of Ra indicating the transition, beyond which the fluctuation $langle theta_{rm rms}rangle _{V}$ has a power law dependence on Ra, given by $langle theta_{rm rms}rangle _{V}{sim }{Ra}^{-0.14pm 0.01}$. |
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| Keywords: | Rayleigh-Bénard temperature fluctuation distribution patterns critical value |
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