RESUMO
Urban morphology affects airflow, causing pollutant accumulation within the urban canopy. Urban planning can regulate urban form by applying such strategies as defining urban block typology and stipulating urban indices. Consequently, urban planning can contribute to a healthy environment. In this context, modeling pollutant dispersion can assist urban planning decisions. Nonetheless, there is a lack of studies investigating the combined impact of urban block typology and urban indices on air quality. Therefore, this study aims to analyze the impact of these combined strategies on pollutant dispersion. Using computational fluid dynamics techniques, we investigated three combinations of urban indices (floor area ratio, surface coverage, and height) for three urban block typologies (single-block, detached building, and central courtyard). A total of nine urban configurations were distributed into three sets of urban index values for the three block typologies, namely "basic cases," "1-cases," and "2-cases." We used the Unsteady Reynolds-Averaged Navier-Stokes equations and the κ-ω SST turbulence model for the numerical simulations. The validation was conducted using wind tunnel experimental data. To assess city breathability at pedestrian height we used five parameters: pollutant concentration, the mean age of air, net escape velocity, and pollutant mass fluxes. The results showed that both strategies (i.e., block typology and urban indices) affect urban air quality. However, the performance of a block typology depends on the urban index values. For instance, in the "2-cases," decreasing the surface coverage by increasing the building's height improved ventilation efficiency in all typologies. Nonetheless, this strategy changed the performance ranking of the "basic cases." In "basic cases" the single-block typology had the best performance; in the "2-cases," the courtyard typology performed best. Although the courtyard typology improved air quality inside the patio, the outdoor areas displayed more pollutant concentration. Finally, general orientations to developing urban planning strategies were formulated.
