*Department of Environmental Technology Management, College for Women, Kuwait University, P.O. Box 5969 Kuwait, Safat 13060, Kuwait
**Faculty of Engineering, Assiut University, Assiut 71516, Egypt
***Academy of Sciences of the Czech Republic, Prague
E-mail: mohamed_f_yassin@hotmail.com
ABSTRACT
The flow and gaseous dispersion emitted from motor vehicles in urban street canyons were experimentally simulated in a boundary layer wind tunnel under neutral atmospheric conditions using a tracer gas emitted from a line source without buoyancy. The flow and diffusion fields in the urban canyons were examined for three street configurations: (1) Regular-shaped intersection, (2) T-shaped intersection and (3) Skew-shaped intersection. Details of the flow and dispersion field were reported that includes the structures of the mean flow field, turbulence intensity, turbulent kinetic energy, Reynolds stress and concentration of pollutant emissions. The results obtained show that: (a) flow and pollutant demarcations behavior depend on the street intersection orientations; (b) there is a stronger influence of the vortex structure on the flow field and pollutant dispersion in the canyons; (c) the regular intersection model is in the skimming flow regime with the vortex forming in the street canyon; (d) flow in the street canyon was dominated by quarter recirculation for the Skew-shaped intersection; and (e) concentration of the emissions for the skew-shaped intersection was higher in the lower region and was gradually decreasing toward the upper region in the canyon. The results from these experiments are useful for predicting the air quality within urban canyon intersections.
Keywords: Atmospheric turbulence; isolated building; pollutant dispersion; Wind tunnel