城市街谷几何结构对街谷内流场及污染物浓度场影响的数值模拟

利用数值模拟方法研究了微尺度街道峡谷范围内街谷几何结构及街道两侧建筑物高度对称性对街谷内流场及机动车排放污染物扩散规律的影响。结果表明:当街道峡谷高宽比>2.1时,街谷内的流场结构由一个完整的垂直涡旋变为上下两个反向运动的强弱不同的垂直涡旋。各类型街谷内污染物扩散水平从强到弱依次为迎风面建筑物高度大于背风面建筑物高度的街道峡谷,迎风面建筑物高度小于背风面建筑物高度的街道峡谷;平行型街道峡谷。

Numerical Simulation of the Effect of Street Canyon Structure on Wind and Pollutant Concentration Fields inside Street Canyon

The diffusive characteristics of vehicle emission pollutant and the wind field characteristics in urban street canyons depend on street canyon ration of height to width, A and the symmetry of building height. In this article, a numerical model was used to study the relationship between street canyon characteristics and diffusive and wind characteristics. It shows that when %A% is more than 2.1, a stable vortex formed within the urban street canyon become two vortexes. The diffusive levels of the pollutant from urban street canyons in the order of from strong to weak strength are the street canyons in which the building heights in windward are highter than that of in leeward, the building heights in windward are lower than that of in leeward, and the street canyons with a series of parallel to each others, respetively.