• 关键词：街谷  气温层结  热力作用  污染物扩散  数值模拟

• 基金项目：国家自然科学基金(No.40805004);深圳市科技研发资金基础研究计划项目(No.201006020747A); 公益性行业(气象)科研专项(No. GYHY200906026)

• 李磊
• 深圳市气象局, 深圳市国家气候观象台, 深圳518040

• 房小怡
• 北京市气象局, 北京市气候中心,北京 100089

• 张立杰
• 深圳市气象局, 深圳市国家气候观象台, 深圳518040

• 摘要：利用CFD数值模拟方法研究了气温层结与地面加热作用对街谷环流和污染物扩散的影响.针对高宽比为0.5和1.0的两种街谷,总共进行了18组敏感性数值试验,结果表明相对于气温层结,地表加热是决定街谷附近污染物扩散能力的更为重要的因素,地表加热作用可显著提高街谷的扩散能力.在地表存在加热的情况下,流场结构、空气交换系数、湍流强度总体上均朝着有利于清除街谷内污染物的方向发展,即使是在稳定层结下,地表加热作用所产生的热力环流也会使得污染物能够被有效地输送和扩散到街谷之外,从而使得近地面的污染物浓度下降.

• Abstract：Based on the computational fluid dynamics (CFD) method, the influences of air temperature stratification and ground heating on the flow field and the diffusion process in street canyon are studied. Aiming at two kinds of street canyons with depth-width ratios of 0.5 and 1.0, respectively, 18 numerical sensitivity tests are performed. The results of the numerical tests show that the ground heating plays a more important role than the air temperature stratification in the pollutant diffusion process in street canyon. The analysis shows that ground heating is able to remarkably promote the diffusion capability in the street canyon. When ground heating exists, the variations of the flow structure, the air exchange rate and the turbulence intensity generally tend to be favorable in removing the pollutant in the street canyon. Even under the condition of stable stratification, thermal circulation induced by ground heating is also able to transport and disperse the pollutant out of the street canyon, and consequently leads to the dropping of the pollutant concentration near ground.

• Key words：street canyon  air temperature stratification  thermodynamic effect  pollutant diffusion  numerical simulation

• 
  摘要点击次数： 1666 全文下载次数： 3949