兰州城区街道峡谷内流场及机动车排放污染物扩散规律研究

利用数值模拟方法对兰州城区街道峡谷内流场及机动车排放污染物扩散特征与街道峡谷风场、几何结构及两侧建筑物对称性这间的复杂关系进行了数值实验。结果表明：在街道峡谷特殊地形和当地气象条件共同作用影响之下，峡谷内会形成一个完整的涡旋流场，其强度随着街道两侧建筑物屋顶来流强度的增大而增大，机动车排放污染物浓度的高层建筑物背风面及街道地面产生堆积，形成高浓度区，随着建筑物屋顶来流风速的增大，涡旋强度增大，湍流混合加强，大气扩散速率增大，峡谷内污染物浓度相对减小。

A Study on air pollutant dispersion in Lanzhou urban street canyon

In order to predict the air pollutant dispersion in an urban street canyon,a two dimension air quality numerical model was developed,based on NavierStokes equations and atmospheric convection diffusion equation.Then this model is used to study the flow and concentration properties in Lanzhou urban street canyon.The study shows that a stable vortex was formed within the urban street under the influence of street canyon geometry and inflow wind and pollutant concentrations have high values on the leeward side and on the ground.It is also found that the pollutants are more diluted with higher inflow wind.