Study of the effects of building density and overall shape of a city on pollutant dispersion by combination of wind tunnel experiments and CFD simulations

Despite the improvement made in controlling local air pollution, urban areas are undergoing increasing environmental pressures and poor air quality is one of the major concerns. Recently, much attention has focused on the relationship between urban form and sustainability. There are indications that the density and the overall shape of cities can have implications on street level ventilation and the "compact city" is by many regarded as the most sustainable urban form. In this framework, this paper is devoted to the study of flow and pollutant dispersion from a ground level line source at pedestrian level within different urban configurations. The urban-like configurations vary from the scenario of an urban sprawl to the opposite scenario of a compact city. Wind tunnel experiments and CFD simulations are performed to evaluate pollutant concentrations in each of the idealized city structures. The overall aim is that of assessing and clarifying the effect of city density on atmospheric flow patterns and pollutant dispersion.