Impact of Roof Shape on Micro-environment in Street Canyons by Numerical Simulation

With the rapid development of urbanization, the changes of urban micro-environment caused by the underlying surface are becoming obvious. The influence of roof structure on the single physical field (such as wind field or temperature field) in the urban micro-environment has been emphasized, while the coupling of two physical fields has been neglected. This paper introduces a model to study the effect of building roof shape on urban micro-environment and the model includes two sub-models, that is computational fluid dynamics (CFD) model and radiation (RAD) model. The two-dimensional numerical model was constructed with four roof-shaped structures and three typical solar incidence angles to simulate the micro-environment in street canyons. Then, the mathematical-physical model was validated by comparing the results of wind tunnel experiment. The results show that the model can simulate urban micro-environment. Moreover, flat roof buildings are more conducive to mitigating the urban heat island effect, and the canyon heat island effect formed by triangular roofs is the strongest, while the downward roof buildings are bad for the heat diffusion on the windward side.