The Effect of the Street Canyon Length on the Street Scale Flow Field and Air Quality: A Numerical Study
The problems associated with urban atmospheric pollution have received increasing attention in the past decades. The residence time of a pollutant within a street canyon is a very important factor that affects both the study of hot spots and the chemical reactions that take place within the street canyon. An example for such chemical reactions are the photocatalytic reactions that take place on the wall surfaces of a street canyon covered with TiO2, like the ones studied in the PICADA project within EC’s 5th Framework Programme. In the frame of this project, a field experiment took place in Guerville, France, which was designed in order to evaluate the performance of translucent TiO2 coatings and also validate the microscale model MIMO which is suitable for street canyon applications. On this basis, a 3D study of the effect of the street canyon length on the flow field and the dispersion of pollutants within street canyons was undertaken. During this study, several numerical simulations for street canyons of the same height and width and therefore aspect ratio but different lengths have been performed, using MIMO as well as the commercial CFD code CFX TASCflow (URL 1). Additionally, a 2D simulation for a street canyon of the same aspect ratio was performed and the results obtained for the residence time and the flow field were compared.
KeywordsStreet Canyon Horizontal Level Urban Street Canyon Windward Wall Rooftop Level
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