Numerical Simulation Of Vehicle Pollutant Dispersion In Street Canyon Based On The Influence Of Road Greenbelts

In view of the current serious motor vehicle exhaust pollution, the frequent fog haze weather. On the basis of predecessors’ research work, this article combines fluid mechanics, traffic engineering and environmental science discipline knowledge, using numerical simulation method, studies the influence law of road greenbelts form and arrangement on motor vehicle tail gas diffusion, and makes a preliminary discussion about particles diffusion and distribution in street canyon. Which can guide the construction of the future urban road greenbelts scientifically, find out particles dispersion characteristics in road greenbelts street canyon. So as to improve residents’ life quality and realize the sustainable development of urban construction and transportation. In this paper, the main works are as follows:Combining foreign wind tunnel experiment, set greenbelts as porous medium, using standard k-ε turbulent model and components transport equation by numerical simulation method, studied the effect of road central green crown height and width to pollutant dispersion and distribution in the street canyon. According to the reality of different greenbelts arrangement, studied the difference of pollutant diffusion and distribution in the street canyon with W/H=0.5,1,1.5 and 2, when the road greenbelts was arranged leeward side, central, windward side and on both sides.On the basis of the three-dimensional model, discussed the influence of tree spacing and road greenbelts length distribution in street canyon on pollutant dispersion and distribution. First set the tree spacing of 0.2,0.4,0.8 and 1.2 H. Analyzed the influence law of tree spacing on pollutant diffusion. Then decreased no greenbelts length on both ends of the street canyon, simulate pollutant diffusion and distribution in the street canyon with greenbelts length of 9.6H,8.8H, 8.0H,7.2H.For understanding the diffusion and distribution characteristics of particles in street canyon, based on the analysis of gaseous pollutants. Selected DPM discrete phase model, studied the diffusion and distribution of 0.1μm, 1μm,20μm,50μm four different diameter particles in street canyon, and compared with 2.5μm diameter particles studied in verification scheme. Then further explored the effect of different wind speed series on particle pollutant diffusion and distribution.