The investigation of street canyon flow field and pollutant diffusion under the coupling effect of dynamic air flow field and roof angle

Abstract

Based on Computational Fluid Dynamics theory, the Euler-Lagrangian method was used to study the effects of three-dimensional dynamic airflow structure and roof angle on the flow structure and pollutant distribution in street canyons. The results show that the variation of inlet airflow speed could influence the airflow structure of street canyon seriously under the dynamic airflow. The airflow structure and pollutant distribution were compressed firstly and then expanded with the increase and decrease of the incoming airflow speed, respectively. The time-varying total pollutant concentration and the concentrations within the pedestrian height zone were increased sharply and then decreased with the increase in roof angles. According to the evolution of the total pollutant concentration and the concentrations within pedestrian height zone with different roof angles, we concluded that the street canyon with roof angle of 25°–30° can provide a clean and livable room for the residents.