Characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh-Bénard convection  

作　　者：Ming-Wei Fang Jian-Chao He Zhan-Chao Hu Yun Bao 方明卫;何建超;胡战超;包芸(School of Aeronautics and Astronautics,Sun Yat-sen University,Guangzhou 510275,China)

机构地区：[1]School of Aeronautics and Astronautics,Sun Yat-sen University,Guangzhou 510275,China

出　　处：《Chinese Physics B》2022年第1期395-402,共8页中国物理B（英文版）

基　　金：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).

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 1×10^(8)≤Ra≤1×10^(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 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≤5×10^(9),the profiles ofθrms/θrms,max descend,then ascend,and finally drop dramatically as z/δincreases.While for Ra≥1×10^(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 hθrmsiV has a power law dependence on Ra,given by hθrmsiV∼Ra−0.14±0.01.

关 键 词：Rayleigh-Benard temperature fluctuation distribution patterns critical value 

分 类 号：O357.5[理学—流体力学]