Analysis and Simulation of Air Pollution in Expressway Toll Station Area: Fid-Bau Portal

Analysis and Simulation of Air Pollution in Expressway Toll Station Area

Wang, Zhanyu / Du, Xuejing

The effects of various factors of the real environment of the toll station area such as wind speed and direction, vehicle flow and buildings on the diffusion of vehicular emission pollutants were explored. The CFD simulation model was set up to simulate the 3D airflow. By using the wind direction frequency weighted method and comparing the simulation result and collected data on the spot, the airflow and the dispersion characteristics of vehicular emission under real atmospheric conditions were predicted. The results show that (1) numerical result agrees well with the measured concentration; (2) airflow whirlpools come into being in the leeward of the buildings and the pollutants assembled around the leeward are difficult to disperse due to the influence of atmospheric boundary layer and layout of the buildings, thus it may be easy to result in locally air pollution; (3) under the condition of the 25°C environmental temperature, $1.9 m \cdot s^{- 1}$ wind velocity, $465 veh \cdot h^{- 1}$ peak hour volume and $0.232 mg \cdot m^{- 3}$ NOx concentration, the characteristic of vehicle emission dispersion is affected by the buildings, meteorological condition and vehicle volume, in the altitude range of $1.5 \sim 2 m$ , the pollutant presents higher concentration.