Characteristics of Airflow and Vehicular Exhaust Pollutant Dispersion in Non-Isolated Urban Street Canyons

The actual urban streets are all non-isolated urban streets.The numerical simulation was used to study the airflow and vehicle emission pollutant dispersion in non-isolated urban street canyons.The numerical results have a good agreement with the experimental data and it is found that the existence of the upstream and downstream buildings of the target street canyon has significant influence on the wind field and concentration distribution by comparing with the results of the previous wind tunnel experiment.The concentration of the vehicle exhausted pollutant is much higher than the concentration in the isolated street canyon.With the increase of the number of upstream and downstream buildings,the wind velocity in the target street canyon is relatively weaker,which results in a higher pollutant concentration in the canyon.It was also found that there exists a critical height when the heights of buildings at both sides are not equal.