Parametric study of the dispersion aspects in a street-canyon area

Abstract

Most modern cities practically consist of street canyons, making monitoring of the level of their pollution an important issue. In this study, a Computational Fluid Dynamics (CFD) simulation of pollutant dispersion was performed for a real, complex-geometry street canyon for various wind directions and speeds. Typical street-canyon effects – like the formation of a longitudinal vortex for wind flow perpendicular to the street axis, or the high concentration levels along the middle of the street for wind flow parallel to the street axis – were observed even in this complex geometry street canyon. Conversely, three dimensional vortices and secondary flows were noticed, resulting in complex flow patterns and pollution hot-spots that proved the important role of CFD in parametric analysis and decision support. The study was performed in order to optimise the positioning of optical pollution measuring instruments inside the canyon area by providing the paths of maximum average concentration.