Keeping the street geometry acceptable in an urban area has become an important task to improve the air quality. Gaseous emissions from vehicles increase the incidence of a variety of human health problems. This study presents a numerical simulation of the effect of street geometry on the dispersion of vehicular pollutants in an urban area using various types of
turbulence models, i.e., a standard
model, a RNG
model and a realisable
model. Three scenarios of street geometry (narrow, intermediate and wide) were examined. The numerical simulations were evaluated and validated against wind-tunnel results to examine model performance measures. The numerical results agreed well with the wind-tunnel results. The results from this work indicated that that the wind velocity increases as the street width increases. A vortex forms within the street canyon of intermediate and wide streets. The concentration of the narrow street is demonstrated to be higher than that for the intermediate and wide streets. Thus, the urban air quality can be improved based on adjustment of street geometry.
Keywords: atmospheric diffusion, CFD models, structural geometry, vehicle emissions