Study On Building Wind Environment And Pollutant Diffusion Under Thermal Conditions

The growing urban population has created a shortage of construction land,resulting in an increasing number of high-rise buildings and dense residential buildings.Local strong winds in these dense building complexes can make it difficult for pedestrians to walk,and in low wind speed areas,the accumulation of harmful gases cannot spread due to poor ventilation,which brings trouble to people’s lives.Therefore,it is urgent to conduct research on the current urban wind environment and pollutant diffusion.At present,the research on wind environment and pollutant dispersion under thermal conditions is mainly concentrated in the fields of street canyons and atmospheric stratification,and the targeted analysis of actual residential areas is still very lacking,especially,qualitative and quantitative analysis of wind environment and pollutant diffusion considering thermal effects has not been reported.This paper analyzes the urban wind environment and pollutant dispersion under thermal conditions,reveals the general law of city wind environment and pollutant distribution,and provides basis for improving wind environment around buildings and improving city’s pollution diffusion ability,related work is as follows:(1)This paper introduces the research background and significance of this paper,describes in detail the research status of building wind environment and pollutant diffusion,as well as the impact of thermal factors on wind environment and pollutant diffusion,and then expounds the research purpose and work of this paper.(2)Numerical simulation of the wind environment and pollutant diffusion around a single building under thermal conditions is carried out to reveal the flow field distribution and pollutant diffusion mechanism of a single building under thermal conditions.By adding source terms to balance the atmospheric boundary layer,using self preservation SST k-ε and taking the standard building group as the research object,in-depth analysis of the flow field and pollutant concentration of four architectural forms of different building density,average height,falling height and the highest building height are carried out.The detailed distribution of wind field,turbulent kinetic energy,reynolds stress and pollutant concentration under different architectural forms is obtained,and the distribution pattern of flow field and pollutant dispersion under different architectural forms is revealed.(3)Relevant conclusions based on single building,numerical simulation is used to study the impact of thermal conditions on the surrounding wind environment and the diffusion of pollutants in the residential area.Obtain the detailed distribution law of wind environment and pollutant concentration of the vertical center of the community y/H=0 the vertical center of the U building and the pedestrian height under thermal conditions.Provide scientific data support to improve the outdoor wind-heat environment of the residential area.(4)Taking a residential area in Changsha as the research background,the wind environment and pollutant dispersion were studied in large scale wind tunnel 10m×3m.A comprehensive analysis of factors such as thermal factors,wind direction,layout,vegetation and other factors is conducted to quantitatively reveal the influence of thermal effect on the convection field,and obtain detailed distribution of wind field and pollutant in the area,which can provide reference for city planning and residential area layout.