Research On The Wind Environment And Particle Diffusion Of Urban Canyon

In recent years,with the intensification of urbanization,a large number of people flock to the cities.The buildings have shown a tall and dense distribution feature and formed a unique style of urban canyon.The air and pollutants in the canyon exchange with the free flow of air at the top of canyon,thus forming a unique micro-scale climate and environment in the canyon.The wind environment,as the core component of the micro-scale climate,has an important link with the thermal and humid environment as well as the air pollution in the canyon,besides it is also the key strategy to solve the problem of urban heat island,fog and haze.Therefore,the urban canyon wind environment and particle pollution control have become an important subject need to deal with.Both experimental measurement and numerical simulation were used to study wind field environment and pollutant diffusion in urban canyon.According to the actual data of the typical canyon in Shen yang,we adopted the ORIGIN software and analyzed the spatial distribution characteristics of particulate matter and the correlation with wind speed,temperature and traffic flow.Used the CFD simulation technology in order to analysis the wind environment characteristics and pollutant diffusion ability of different geometric ideal canyon.From the perspective of urban planning,we simulated and analyzed the outdoor wind environment under different planning schemes of block buildings,and put forward the reasonable suggestions about commercial block planning.The results showed that:The pollutants distribution measured by experimental measurement was influenced by many factors in the canyon,and the pollutants mass concentration presented a certain regularity,the maximum and minimum appeared alternately.The wind environment in urban canyon simulated by PHOENICS showed that air flow appears a clear turbulence eddy,contamination was not easy to spread and the air quality was poor;The wind field environment of asymmetric urban canyon was better than that of symmetrical urban canyon,and the wind turbulence intensity of "Up step" was higher than "Down step",the asymmetric urban canyon was Minimum.The actual canyon pollutant distribution was complicated due to the complex and irregular distribution of contamination sources and complicated wind environment.The podium of commercial canyon and high-rise buildings made the practical pollutant concentration distribution more complex.It could be found from the wind environmental simulation analysis of three types of planning schemes about the wind environment under winter and summer that a reasonable construction planning of block buildings plays an important role on canyon and outdoor wind environment.Therefore,the study on the shape factors of urban canyon and blocks planning based on the wind environment and the ability of pollutant diffusion in canyon has important significance to reduce the particle pollution and improve the air quality.Using the CFD numerical simulation software to evaluate the wind environment in the canyon and solve the problem of the current severely air pollution in cities has an important role to prevent and control atmospheric pollution and guide urban planning.