Influence of Urban Street Valley Distribution Pattern on Traffic Pollutant Diffusion
In this study,the influence of building distribution pattern on wind field and pollutant concentration field in street valley was studied by numerical simulation.The results show that for the symmetric street valley,the overall wind direction in the street valley rotates counterclockwise with the increase of the height-to-width ratio of buildings.Secondary vortices appear when the height-to-width ratio is 3,and the main dilution area of pollutants is from the top of the street valley to the front and back sides of the street valley.The average surface concentration is the largest when the height-to-width ratio is 2.For the"rising"street valley in the asymmetric street valley,with the increase of the height of windward buildings,the backflow effect and the dilution efficiency of pollutants are en-hanced,and the windward pollutants can be removed and the overall average concentration of the surface is reduced.As for the"de-scending"street valley in the asymmetric street valley,clockwise main vortex and counterclockwise secondary vortex with a large influence range are generated.With the increase of leeward building height,the transition area between the two vortices is enlarged and the back-flow effect is enhanced,and leeward pollutants are completely removed and the average surface concentration decreases.The distribution of traffic pollutants is significantly different with the pattern of street valley in different cities.Therefore,the rational urban layout can be used as an effective way to alleviate traffic pollution.
万方数据
维普
