High resolution wind-tunnel investigation about the effect of street trees on pollutant concentration and street canyon ventilation

Greening cities is a key solution to improve the urban microclimate and mitigate impact of climate change. However, effect tree planting on pollutant dispersion in streets still debated topic. To shed light this issue, we present wind-tunnel experiment aimed at investigating trees street canyon ventilation. An idealized district was simulated by an array blocks, two rows model were arranged sides oriented perpendicularly with respect wind direction. Reduced scale chosen mimic realistic shape aerodynamic behaviour. Three different spacings between considered. A passive scalar injected from line source placed ground level concentration measurements performed whole canyon. Results show that presence alters pattern progressive shift nearly two-dimensional three-dimensional field depending density. Despite significant change induced trees, average pollution street, thus overall ventilation efficiency, does not specific trend density trees.