On the influence of viaduct and ground heating on pollutant dispersion in 2D street canyons and toward single-sided ventilated buildings

Özet

This paper employs Computational Fluid Dynamic (CFD) simulations to investigate the influence ofground heating intensities and viaduct configurations on gaseous and particle dispersion within twodimensionalidealized street canyons (typical aspect ratio H/W ¼ 1) and their transport from outdoorto leeward and windward rooms of naturally-ventilated buildings. Without viaduct, the ground heatingexists at the street ground above which the pollutant source is located, while in the presence of viaductthe ground heating only occurs at the viaduct ground surface and pollutant source is slightly above theviaduct. Results show that viaduct significantly reduces overall spatial mean indoor concentrations ofgaseous pollutant ( ) and indoor particle number (PN) in all rooms being the elevated pollutantsource above the viaduct compared to those without the viaduct. Road barriers on the viaduct slow downthe flow above it and slightly increase indoor , but they reduce indoor PN due to the enhancedparticle deposition onto viaduct surfaces. The uniform heating of street ground or viaduct ground surfacestrengthens recirculation flows in street canyon, reducing and PN of fine particle (diameterd ¼ 1 mm), but for larger particles indoor PN distribution is complicated by the interaction of gravity,buoyancy and wind-induced recirculation. Although further investigations are still required to propose apractical framework on viaduct design, this paper is one of the first attempts to study the effect of viaducton street pollutant dispersion.