Amplitude modulation of turbulence intensities and fluxes in urban convective boundary layers

Zhou，Kangcheng1,2,3; Liu，Chun Ho3; Mei，Di3; Wu，Buchen1,2,4; Wan，Minping1,2

2024-09-01

10.1016/j.ijheatmasstransfer.2024.125706

International Journal of Heat and Mass Transfer   影响因子和分区

0017-9310

Despite extensive research on the effect of atmospheric stability, the influence of convective rolls and thermal plumes in convective boundary layer (CBL) on urban winds and turbulence remains merely understood. Using amplitude modulation (AM), we examine the multi-scale interaction among turbulence intensities, fluxes, and large-scale CBL structures in unstable urban boundary layers (UBLs). Nine sets of large-eddy simulation (LES) are conducted, contrasting the CBL behavior over idealized urban morphology from neutral to free convection. This study, comparing the stability-dependent AM coefficient, reveals a tight modulation of small-scale turbulence and fluxes at urban canopy layer (UCL) by different types of characteristic CBL structures. Wavelet analysis corroborates their interactions in the time-frequency domain. Moreover, the correlation between the AM and the coherent CBL structures in the mixed layers is unveiled. Additionally, building-induced secondary flow structures are observed to dominate the modulation of small-scale turbulence residing within. UCL building-scale turbulence exhibits a higher susceptibility to modulation compared with intermediate scales. Notably, strong convection can invert the phase relationship between large scales and UCL turbulence. These results signify the crucialness of considering CBL coherent structures in the development of land-surface-parameterization schemes as well as the cautious implementation of predictive models in urban CBLs.

Amplitude modulation Coherent structures Turbulent convection Unstable stratification Urban turbulence

SCI ; EI

英语

第一 ; 通讯

20242116134676

Amplitude modulation ; Atmospheric thermodynamics ; Boundary layer flow ; Boundary layers ; Frequency domain analysis ; Heat convection ; Large eddy simulation ; Morphology

Atmospheric Properties:443.1 ; Fluid Flow:631 ; Fluid Flow, General:631.1 ; Thermodynamics:641.1 ; Heat Transfer:641.2 ; Mathematics:921 ; Mathematical Transformations:921.3 ; Physical Properties of Gases, Liquids and Solids:931.2 ; Materials Science:951

ENGINEERING

2-s2.0-85193696957

Scopus

1.Guangdong Provincial Key Laboratory of Turbulence Research and Applications,Department of Mechanics and Aerospace Engineering,Southern University of Science and Technology,Shenzhen,518055,China
2.Guangdong-Hong Kong-Macao Joint Laboratory for Data-Driven Fluid Mechanics and Engineering Applications,Southern University of Science and Technology,Shenzhen,518055,China
3.Department of Mechanical Engineering,The University of Hong Kong,7/F, Haking Wong Building, Pokfulam Road,Hong Kong
4.Department of Mechanical and Aerospace Engineering,The Hong Kong University of Science and Technology,Clear Water Bay,Hong Kong

Zhou，Kangcheng,Liu，Chun Ho,Mei，Di,et al. Amplitude modulation of turbulence intensities and fluxes in urban convective boundary layers[J]. International Journal of Heat and Mass Transfer,2024,229.

Zhou，Kangcheng,Liu，Chun Ho,Mei，Di,Wu，Buchen,&Wan，Minping.(2024).Amplitude modulation of turbulence intensities and fluxes in urban convective boundary layers.International Journal of Heat and Mass Transfer,229.

Zhou，Kangcheng,et al."Amplitude modulation of turbulence intensities and fluxes in urban convective boundary layers".International Journal of Heat and Mass Transfer 229(2024).