Large Eddy Simulation and Study of the Urban Boundary Layer

作     者：苗世光 蒋维楣 

作者机构：Department of Atmospheric Sciences Nanjing University Nangjing 210093 Institute of Urban Meteorology China Meteorological Administration Beijing 100089 Department of Atmospheric Sciences Nanjing University Nangjing 210093ased on a pseudo-spectral large eddy simulation (LES) model an LES model with an anisotropy turbulent kinetic energy (TKE) closure model and an explicit multi-stage third-order Runge-Kutta scheme is established. The modeling and analysis show that the LES model can simulate the planetary boundary layer (PBL) with a uniform underlying surface under various stratifications very well. Then similar to the description of a forest canopy the drag term on momentum and the production term of TKE by subgrid city buildings are introduced into the LES equations to account for the area-averaged effect of the subgrid urban canopy elements and to simulate the meteorological fields of the urban boundary layer (UBL). Numerical experiments and comparison analysis show that: (1) the result from the LES of the UBL with a proposed formula for the drag coefficient is consistent and comparable with that from wind tunnel experiments and an urban subdomain scale model (2) due to the effect of urban buildings the wind velocity near the canopy is decreased turbulence is intensified TKE variance and momentum flux are increased the momentum and heat flux at the top of the PBL are increased and the development of the PBL is quickened (3) the height of the roughness sublayer (RS) of the actual city buildings is the maximum building height (1.5-3 times the mean building height) and a constant flux layer (CFL) exists in the lower part of the UBL. 

出 版 物：《Advances in Atmospheric Sciences》 (大气科学进展（英文版）)

年 卷 期：2004年第21卷第4期

页      面：650-661页

核心收录：

学科分类：07[理学] 070601[理学-气象学] 0706[理学-大气科学] 

基　　金：The research was supported by the National Natural Science Foundation of China under Grant Nos.40333027 and 40075004 

主　　题：uniform underlying surface urban boundary layer planetary boundary layer large eddy simulation (LES) anisotropy turbulent kinetic energy closure model 

摘      要：Based on a pseudo-spectral large eddy simulation (LES) model, an LES model with an anisotropy turbulent kinetic energy (TKE) closure model and an explicit multi-stage third-order Runge-Kutta scheme is established. The modeling and analysis show that the LES model can simulate the planetary boundary layer (PBL) with a uniform underlying surface under various stratifications very well. Then, similar to the description of a forest canopy, the drag term on momentum and the production term of TKE by subgrid city buildings are introduced into the LES equations to account for the area-averaged effect of the subgrid urban canopy elements and to simulate the meteorological fields of the urban boundary layer (UBL). Numerical experiments and comparison analysis show that: (1) the result from the LES of the UBL with a proposed formula for the drag coefficient is consistent and comparable with that from wind tunnel experiments and an urban subdomain scale model; (2) due to the effect of urban buildings, the wind velocity near the canopy is decreased, turbulence is intensified, TKE, variance, and momentum flux are increased, the momentum and heat flux at the top of the PBL are increased, and the development of the PBL is quickened; (3) the height of the roughness sublayer (RS) of the actual city buildings is the maximum building height (1.5-3 times the mean building height), and a constant flux layer (CFL) exists in the lower part of the UBL.