摘要
以纳维斯托克斯方程组、大气平流扩散方程、湍流动能及湍流动能耗散率方程组为基础, 采用伪不定常方法, 建立了一个数值模式, 利用该模式对城市湍流边界层内流场结构及汽车排放污染物扩散规律进行了研究。结果表明: 街谷内会形成一个涡旋型流场, 汽车排放污染物浓度在地面及建筑物背风面产生堆积, 且其沿高度方向的梯度变化在背风面大, 迎风面小。随着街谷两侧建筑物屋顶风速的增大, 峡谷内形成的涡旋流场的强度增大, 污染物扩散速率增大; 当屋顶来流与街道之间的夹角逐渐增大时, 涡旋中心位置由街道中心偏向于背风面及更高层且污染物扩散速度加快。
A numerical model is developed based on Navier-Stokes and K-E equations, and as well as the method of artificial compression. Then the structure of the flow and the characteristics of vehicle emission pollutants in urbal turbulent boundary layer are studied through the numerical model. The result shows that a vortex can be formed in urban street canyon. The concentration of vehicle emission pollutant are stacked on the leewind side of building and the ground, and its gradient change along vertical direction is higher on the leewind side, and low on the windward side. When the wind speed of both sides of building in street canyon is faster, the intensity of vortex flow field is stronger, the speed of pollutant emission is faster, too. When the inflow wind direction towards the street, The center of the vortex is tilt toward leewind side or higher, the released pollutants from urban street canyons become more diluted.
出处
《高原气象》
CSCD
北大核心
2005年第2期167-172,共6页
Plateau Meteorology
关键词
湍流边界层
数值模拟
汽车尾气
Turbulence boundary-layer
Numerical simulation
Vehicle emission pollutants
