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Large Eddy Simulation and Study of the Urban Boundary Layer

         

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.

著录项

  • 来源
    《大气科学进展:英文版》 |2004年第4期|650-661|共12页
  • 作者

    苗世光; 蒋维楣;

  • 作者单位

    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.;

  • 原文格式 PDF
  • 正文语种 chi
  • 中图分类 P434.1;
  • 关键词

    城市边界层; 大旋涡仿真; 各向异性; 混乱动力能量关闭模型;

    机译:均匀下垫面;城市边界层;行星边界层;大涡模拟(LES);各向异性;湍动能封闭模型;
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