The prediction of PM2.5 dispersion in Bangkok (Pathumwan district)using CFD modeling

Abstract

City configuration, meteorological conditions and emission source are the important factors affecting the concentration and dispersion of pollutants within urban street canyon. The dispersion of PM2.5 in Pathumwan district, Bangkok which has a characteristics of street canyon was predicted using a Computational Fluid Dynamics (CFD) model. Flow and dispersion of PM2.5 were analyzed using standard k-ε turbulence model. The concentrations of PM2.5 were investigated under different conditions to demonstrate the effect of city configuration in study area, meteorological characteristics, and lockdown due to COVID-19 on PM2.5 concentration. The numerical model was validated with the measured data from the air quality monitoring station of the Environment Bureau, Bangkok. The reduction of emission rate during lockdown period causing the PM2.5 concentration decreased by 25.24 percent from normal time. Besides, the city configuration with the skytrain structure increases PM2.5 concentration at the area under the skytrain by 21.6 percent and at the area away from the skytrain by 7.05 percent. Moreover, meteorological conditions must also be taken into account especially wind speed and direction. Finally, the results obtained from simulation will be used for proposing the guidelines to reduce the concentration of PM2.5.