Mehdi Jahangiri - Department of Mechanical Engineering, Islamic Azad University, Shahrekord branch, Iran
Reza Babaee Osboee - Mechanic Master of Science, Isfahan University of technology, Iran
Alireza Hajji Malayeri - Mechanic Master of Science student, Isfahan University of technology, Iran

In this paper numerical simulation of pollutant concentration in a street canyon of urban area at aspect ratio 4 by using Fluent software has been studied. In this simulation two-equation turbulence model of k-epsilon and species transport without reaction, respectively, are used for investigate the flow field and distribution of pollution within the street canyon. Also computational domain is divided by Gambit software. For pollution simulation from vehicle emissions, a pollution source in the middle line of the street is considered. From results of speed of 55 meters per second for wind flow, analysis of stream lines show that vortex flow in duct, easily connected to free flow and thus dilution of pollution will be faster. Also diagram of concentration shows that pollution concentration near the leeward wall about eight times greater than windward wall.

Pollutant concentrations, street canyon, aspect ratio, windward wall, leeward wall