Numerical Simulation Study of Particles Dispersion in Urban Street Canyon

Based on the CFD technique, the airflow and particle dispersion inside an isolated street canyon were numerical studied in this work. Using the discrete phase model (DPM), inside a symmetric street canyon,in view of different aspect ratios (B/H=1 and B/H=0.5 ) and under different wind velocities (U_∞ = 5m/s, 10m/s, 15m/s and 20m/s), numerical simulated the airflow field and the particle dispersion with 1μm particle size. It was found that all cases generated a clockwise vortex inside an isolated street canyon, particles diffused to the leeward surface with airflow. And when aspect ratio is B/H = 0.5 will generate an anticlockwise secondary vortex in the bottom of canyon. Particle deposition on the windward and leeward walls, the road surface and building roofs were evaluated and expressed in terms of capture efficiency. For a high wind velocity of 20m/s, it shows maximun deposition that occurred on the road surface.