Temperature Fluctuation Profiles in Turbulent Thermal Convection: A Logarithmic Dependence versus a Power-Law Dependence

He, Yu-Hao1; Xia, Ke-Qing1,2,3

2019-01-10

10.1103/PhysRevLett.122.014503

PHYSICAL REVIEW LETTERS   影响因子和分区

0031-9007

1079-7114

We report an experimental measurement of the rms temperature (sigma(T)) profiles in two regions inside a large aspect ratio (Gamma = 4.2) rectangular convection cell. It is found that, in the region where the boundary layer is sheared by a large-scale wind, sigma(T) has a power-law dependence on the vertical distance (z) from the plate, whereas in the region where plumes are abundant, sigma(T) has a logarithmic dependence on z. The power-law profile may be understood by balancing the inertia force and the viscous force in the equations of motion, and the logarithmic profile may be understood in terms of the balance between the buoyancy and the inertia forces. When normalized by a convective temperature scale, theta*, the profiles of sigma(T) collapse onto a single curve for different values of the Rayleigh number. This shows that the convective temperature first proposed by Deardorff is the suitable temperature scale outside the thermal boundary layer for both logarithmic and power-law profiles. Our finding suggests a strong connection between plumes and the logarithmic rms temperature profile. The present Letter reveals that multiple force balance mechanisms can coexist in the bulk of highly turbulent flows.

SCI ; EI

英语

通讯

Hong Kong Research Grants Council[CUHK14301115] ; Hong Kong Research Grants Council[CUHK14302317]

Physics

Physics, Multidisciplinary

WOS:000455687000015

AMER PHYSICAL SOC

20190306371010

Aspect ratio ; Boundary layers ; Equations of motion ; Heat convection

Thermodynamics:641.1 ; Heat Transfer:641.2 ; Calculus:921.2

PHYSICS

Web of Science

1.Chinese Univ Hong Kong, Dept Phys, Shatin, Hong Kong, Peoples R China
2.Southern Univ Sci & Technol, Ctr Complex Flows & Soft Matter Res, Shenzhen 518055, Guangdong, Peoples R China
3.Southern Univ Sci & Technol, Dept Mech & Aerosp Engn, Shenzhen 518055, Guangdong, Peoples R China

He, Yu-Hao,Xia, Ke-Qing. Temperature Fluctuation Profiles in Turbulent Thermal Convection: A Logarithmic Dependence versus a Power-Law Dependence[J]. PHYSICAL REVIEW LETTERS,2019,122(1).

He, Yu-Hao,&Xia, Ke-Qing.(2019).Temperature Fluctuation Profiles in Turbulent Thermal Convection: A Logarithmic Dependence versus a Power-Law Dependence.PHYSICAL REVIEW LETTERS,122(1).

He, Yu-Hao,et al."Temperature Fluctuation Profiles in Turbulent Thermal Convection: A Logarithmic Dependence versus a Power-Law Dependence".PHYSICAL REVIEW LETTERS 122.1(2019).