A numerical study of atmospheric pollutant dispersion in different two-dimensional street canyon configurations

The scope of this paper is to study numerically the dispersion of atmospheric pollutants within different street canyon geometrical configurations and building height scenarios. The microscale model MIMO, designed to take into account pollution dispersion in the vicinity of buildings, is validated against a two-dimensional wind-tunnel experiment for a square ( W/ H=1) and a deep canyon ( W/ H=1/2) configuration. It was found that the model performance is satisfactory. Having established this, the study involved the alteration of the building heights bounding the canyon for both square and deep configurations. Furthermore, the effects of different aspect ratios on the pollution dispersion characteristics are investigated. It is demonstrated that, under certain conditions, pollutants disperse more easily, while under others pollutant levels increase, with implications for pedestrian exposure. Furthermore, interaction of air in and above the canyons is investigated under different street geometries. It is found that both street geometry and building height influence the interaction between air inside and above the canyons.