Aerodynamics effects on pollution concentrations of through-passages in building indoors urban street canyon

In this study, the numerical investigation was carried the effects of Through-passages under building in urban street canyons on traffic pollutant dispersion. A three-dimensional computational fluid dynamics (CFD) model is used to evaluate air flow and pollutant dispersion within an urban street canyon using Reynolds-averaged Navier–Stokes (RANS) equations based on k-ɛ turbulence model to close the equation system. The numerical model is performed with ANSYS-CFX code. Whereas vehicle emissions of sulfur hexafluoride (SF6) taken as tracer gas are considered as double line sources along the street canyon. The numerical model was validated by the wind tunnel experiment results. Having established this, the wind flow and pollutant dispersion in urban street canyons. The numerical simulation results agree reasonably with the wind tunnel data. Then, the numerical simulations were extended to explore the impacts of the effects of throughpassages under building on SF6 dispersion; the results indicated that through-passages under building generally increase dispersion of SF6 concentrations in symmetric street canyons. Overall results indicate the decreasing of the concentration normalized in the critical region located on the centerline in the leeward and windward wall successively.