中文摘要：

利用计算流体力学软件Fluent6.3.26提供的大涡模式和国标推荐的AERMOD模式分别对方形建筑物影响下的大气污染物扩散进行了模拟,通过与风洞实验结果的比较,对各模式的模拟能力进行了评价.结果表明,大涡模式对污染物散布特征的模拟与风洞实验结果基本一致,对建筑物顶部、空腔区和尾流区等区域污染物浓度分布的模拟效果均处于可接受水平;AERMOD模式模拟结果与风洞试验结果偏离较远,尤其是对空腔区污染物散布的模拟能力较差,误差较大.与大涡模式Y/H=0平面流场模拟结果对比（H为建筑物高度）,AERMOD模式对风场的假设未能客观地反映建筑物附近气流变化的基本特征,是误差的主要来源之一,建议结合大涡模式订正,提高模拟结果的准确性.

英文摘要：

The effect of buildings on wind flow fields plays a very important role in air pollutant dispersion. Comparison and evaluation of different numerical simulation methods help improve the prediction on pollutant concentrations. Computational Fluid Dynamics （CFD） software FLUENT and the Gaussian model AERMOD were separately used to simulate pollutant concentration around a cube. FLUENT was run in the large eddy simulation （LES） mode, using the Smagorinsky-Lilly closure model, to resolve the larger scales of the flow field. AERMOD model based the classical Gaussian model developed by EPA and AMS considered building downwash. The numerical simulation results were compared with the wind tunnel experiment--Compilation of Experimental Data for Validation of microscale dispersion models （CEDVAL）. The LES model can describe the pollutant dispersion characteristics well, and the simulation capability could be accepted in the whole simulation zone. The simulation capability of AERMOD model on pollutant concentration was poor compared with LES model, especially in the downwind recirculation cavity. The hypothesis of AERMOD model was compared with the numerical simulated results of the large eddy simulation model on wind speeds. It was shown that the simulation errors of AERMOD model on pollutant concentration were from the background wind flow fields.