城市立体交通系统中污染物传播特性数值模拟

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.