Quantitative Analysis And Optimization Strategy Of Spatial Form In Central Urban Area Of Dabu County From The Perspective Of Wind Environment

Taking the central urban area of Dabu County as an example,in the contradiction between the demand of urban scale expansion and the supply shortage of construction land caused by geographical environment constraints,the construction density of urban space is gradually increasing and disorderly,which further weakens the already unsatisfactory urban ventilation capacity.It will lead to the deterioration of urban climate,the increase of micro air density and the enhancement of urban air quality.Therefore,it is of great significance to study the wind environment of this type of city and optimize the spatial form of climate adaptation.Through the quantitative research method of spatial form,this paper analyzes the spatial form indicators such as floor area ratio,building density and average number of floors in the overall research area,and summarizes the spatial form types of the central urban area of Dabu county.Combined with the research method of windward surface density,the distribution of windward surface density in different height ranges reflecting the obstruction of space entities to air flow is calculated,and the potential ventilation corridors of the city are identified.After quantitative analysis,this paper uses CFD simulation software to simulate the wind environment of the research unit in the core research area.Finally,the quantitative analysis and research system of spatial morphology based on wind environment is constructed.Through the coupling analysis of wind environment simulation data and the relevant elements of the research unit,such as the type of spatial form,the value of windward surface density,the index of spatial form,it is proved that the relevant elements reflecting the spatial form are related to the current situation of wind environment in the central urban area of Dabu County:the correlation coefficients of windward surface densityλ_f（0-15m）,λ_f（0-42m）,λ_f（0-99m） and the average wind speed ratio of 1.5m height The results show that there is a strong negative correlation between the windward surface densityλ_f（0-15m） of the podium floor and the space ventilation capacity at the pedestrian height;the ratio of the windward surface densityλ_f（0-15m） to the average wind speed at the height of 1.5m conforms to the linear regression equation,and the goodness of fit R²=0.3507;the windward surface densityλ_f（0-15m） has the strongest correlation with the floor area ratio and building density,and the regression model is logarithmic The goodness of fit of the regression equation is R²=0.7169,R²=0.6054;the regression equation shows that when the building density of the research unit in the central urban area of Dabu county is controlled within 35%,the plot ratio is less than 1.8,and the average number of floors is not more than 7,the spatial form can ensure good air circulation.According to the results of the quantitative and simulation analysis,this paper puts forward the optimization strategies for the wind environment quality from three aspects of the ventilation corridor delineation,the space renewal of the stock land and the urban design of the incremental land.This paper abandons the traditional experience of Building Urban Ventilation corridor in the form of plane,and based on the numerical value of windward surface density at different heights of space and the basic principle of fluid mechanics,puts forward the strategy of identifying and constructing multi-layer and multi-stage ventilation corridor system of three-dimensional urban space;for the renewal of existing land,it puts forward the following suggestions:open the urban ventilation openings,reduce the rate of street openings,comply with the prevailing wind direction of the street,improve the quality of Urban Ventilation corridor system According to the urban design of incremental land use,this paper puts forward some optimization design strategies,such as using the new area space to enhance the local circulation,building group windward facing appropriate orientation and so on.Through different levels of strategic combination,the paper hopes to provide help for the spatial morphology research of small basin cities in the same type of calm wind area in the central urban area of Dabu County,and provide some reference for the climate adaptive urban planning.