In this talk, we investigate the effect of urban form on the dispersion of pollutants at two different spatial scales: at the scale of the district and at the scale of the single street canyon.

Starting from the observation of the urban street pattern at the district scale, the first part of the talk proposes a new perspective based on the theory of complex networks to analyse and model the transport of pollutants along the streets of a city. Adopting this mathematical interpretation, propagation is modelled as a spreading process on a network and the most dangerous areas in a city are identified as the best spreading nodes. The model is suitable to investigate which structural properties of a city make it fragile to air pollution.

The second part of the talk analyses the mechanisms of street canyon ventilation by means of wind tunnel experiments. The external wind is kept perpendicular with respect to the street axis, while conditions at the canyon walls are modified by alternatively heating the walls and by changing the cavity aspect ratio. Two rows of model trees are arranged at the sides of the street to simulate urban vegetation. Results evidence that canyon ventilation is mainly driven by the fluctuating component of the turbulent flow within the canyon.

Short bio: Sofia Fellini obtained her Bachelor Degree in Environmental Engineering at the University of Padua (Italy) in 2013. She then moved to Polytechnic University of Turin (Italy) where she earned a Master Degree in Environmental Engineering in 2015. Between 2015 and 2017 she worked as Research Assistant in collaboration with SMAT (leader company for the integrated water service in Turin). In 2021, she obtained a PhD in the framework of a joint program between Polytechnic University of Turin and Ecole Centrale de Lyon (France). Her thesis was devoted to pollutant dispersion in urban areas.