Abstract:In order to study the spatial and temporal distribution of pollutants as well as the elevated height of the particle, and the distance of pollutant diffusion under different wind speed conditions, a lagrangian particle tracking model based on Multi-Phase Particle-In-Cell (MP-PIC) was used to capture the diffusion of contaminants. The results show that the flow around a square cylinder occurs at low wind speed due to the blocking effect of pollution sources. Moreover, pollutants split into two groups along the downwind direction. The pollutants fluctuate in the computational domain under the influence of turbulence, and the splitting situation always exists persists in the computational domain. When the wind speed is 2 m·s-1, the distance between the splitting groups is 5-20 m, and the maximum number concentration of pollutants is 70-87 per cubic meter m-3 along the downwind direction from 1000 m to 1300 m. When the wind speed increases to 5 m·s-1, the distance between these two pollutants groups is 2-10 m. When the flow field becomes steady, the maximum number concentration of pollutants along the downwind direction from 1000 m to 1300 m is 212-300 per cubic meter m-3. When the wind speed is 10 m·s-1, the splitting phenomenon disappears, and the maximum number concentration of pollutants along the downwind direction from 1000 m to 1300 m is becomes 407-502 per cubic meter m-3.