城市立体交通系统中污染物传播特性数值模拟

构建了一个包含交通转盘、隧道、高架桥和下沉式公交站的立体交通几何模型，建立了该系统中流体流动与污染物传播的耦合数学模型，数值分析了环境风变化时，该系统中流体流动与气态污染物的传播规律.结果表明，环境风向的变化直接改变了公交站区域流体的流向途径，在公交站区域；北风时的平均污染物浓度是西风时的3.5倍，而在转盘中央区域，北风时平均污染物浓度是西风时的5倍.西风时，环境风速从0.5m/s增加到3.5m/s，东侧公交站区域的平均污染物浓度减少95.21%；交通隧道内，环境风速的增加使空气流通速度增加，污染物浓度迅速降低.

Numerical simulation of pollutant propagation characteristics in a three-dimensional urban traffic system

A three-dimensional traffic geometry model consisting of a traffic roundabout, tunnel, viaduct, and a sinking bus station was built, and the mathematical model by coupling the fluid flow and pollutant propagation in this system was established. The fluid and gaseous pollutant flowing in this system was analyzed under the variation of ambient crosswind (ACW) via numerical simulation. The results showed that the variation of ACW direction directly changed the fluid flow path in the bus station. In the bus station area, the average pollutant concentration in north wind is 3.5times that in west wind. While in the middle area of the traffic roundabout, the average pollutant concentration in the north wind is 5times that in the west wind. When west ACW increased from 0.5m/s to 3.5m/s, the average pollutant concentration in the eastern bus station is reduced by 95.21%. In traffic tunnels, increasing ACW speed will both increase the airflow rate and significantly decrease the pollutant concentration.