Numerical Study of Buoyant Flows in Street Canyon Caused by Ground and Building Heating

The urban areas discomfort is related to the increase of local temperatures, which is induced by the large concentration of the built environment, road pavement and the high construction materials thermal capacitance. The particular configuration of buildings arrangement amplifies the population vulnerability and the exposure to pollution. These conditions can be related to the "urban fabric" density, road geometrical characteristics, buildings features and, finally, to the lack of wide-open spaces. An important part of the heat exchange between buildings and the ambient surrounding is due to convective and radiative phenomena. Computational fluid dynamics (CFD) is often used to predict flow structures in urban areas for the determination of pollutant dispersion, human comfort or heat fluxes. During daytime building façades and ground surfaces are heated by solar radiation and thereby they induce buoyancy, which changes the flow field around buildings significantly. A computational fluid dynamics (CFD) model is developed and used to investigate the thermo-fluid dynamic effects inside and above a street canyon. In this study different simulations have been performed and validated, investigating the micro-climatic condition, such as thermal and air velocity fields.