城市街道内污染物扩散的数值模拟

随着我国城市汽车保有量的迅速攀升,城市中心区的空气质量与生态环境急剧恶化.利用CFD数值模拟研究街道峡谷污染物的扩散问题,对比分析了开放街道峡谷和城市街道峡谷污染物的扩散问题,证明了计算域和入流边界处湍动能k和湍动能耗散率ε取值的重要性.计算结果与经典风洞实验符合很好,证实了相同条件下城市街道峡谷的背风墙和迎风墙上的污染物浓度均大于开放街道峡谷的相应值.利用3维建筑群计算实例,指出了寻求建筑群优化布局对减小小区污染的重要性.

Numerical Simulation of Pollutant Dispersion in Urban Streets

With the rapid increase in private cars in cities, the air quality and ecological cycle are deteriorating fast. The pollutant dispersion in street canyons was simulated by CFD in this paper. The importance to choose suitable computation domain and inlet k and c boundary value was verified by comparing the open country street canyon with the urban roughness street canyon. Numerical results showed good agreement with the benchmark experiment. The results also confirmed the experimental finding that the pollutant concentrations of leeward side and windward side in urban roughness street canyon were higher than those in open country street canyon for the same condition. Taking a group of 3-dimensional buildings as an example, it was pointed out that the optimized position of the group buildings was important to reduce the concentration of pollutant around buildings.