Research And Application Of Urban Canopy Pattern Suitable For The Height Inhomogeneity Of Building Groups

At present,most of the researches on the dynamic characteristics of the atmospheric boundary layer influencing the urban building clusters are carried out around the horizontal flow around the building clusters,and the research on the obstructing and dragging effects of the buildings in the vertical direction on the incoming wind is very lacking.At the same time,most of the urban canopy models that have been developed are one-dimensional uniform canopy models,which cannot reflect the influence of the height inhomogeneity of the building complex on the ventilation characteristics in the calculation results,which leads to the impact on the vertical ventilation corridors.The research is very lacking.Therefore,this research is based on the architectural environment major,combined with the related research of urban climate,planning and design,and in-depth study of the influence of the vertical difference on the urban canopy ventilation characteristics of the highly non-uniform building complex,and the construction is suitable for highly non-uniform buildings.The parameterized scheme of the urban canopy model of the building group,a large number of numerical experiments are carried out using this canopy model to obtain a reasonable design of the height layout of the building group.In order to promote the effective vertical exchange of the air above the urban canopy and the air in the canopy,form an effective vertical ventilation corridor,optimize urban ventilation,alleviate the heat island effect,and provide guidance for improving air quality.Aiming at the construction and application of a highly non-uniform quasi-two-dimensional atmospheric dynamic urban canopy model,this paper focuses on the following aspects:1.Based on the spatial morphology of the building complex,a parameterization method for describing the drag coefficients of the high heterogeneity of the building complex affecting the atmospheric dynamics is established to form a set of parameters that can systematically express the non-uniformity of the building.Among them,the windward area index(λ_f)and the plane area index(λ_p)are used to express the unevenness of the building group in the horizontal direction,and the height dispersion(s)is used to express the unevenness of the building group in the vertical direction.Using CFD simulation to study the influence of the above parameters on the drag coefficient,the simulation results show that the standardized overall drag coefficient increases linearly with the increase of the height dispersion of the building group.At the same time,wind tunnel experiments give the scope of application.This part is integrated with the existing urban area microclimate and thermal balance dynamic prediction model(UDC)based on the one-dimensional urban canopy model of the research group,so that it has the ability to reflect the influence of the high heterogeneity of the building group on the ventilation characteristics.2.Based on the spatial form of the building complex,select basic form indicators:street valley width(W),average building height(h),and height dispersion(s)for single-factor controlled variable experiments.CFD simulation is used to explore the influence of each shape index on the ventilation characteristics of the ventilation corridor area and street valley area.A calculation method for calculating the horizontal wind speed(u)and vertical wind speed(w)in the ventilation corridor area and the street valley area based on the space average wind speed of the building base area(the study area of the traditional one-dimensional canopy model)is established.The overall results are examined,and a quasi-two-dimensional zonal calculation model of wind speed integrated with three morphological indicators is obtained.This part of the calculation module is merged with UDC to expand it into a quasi-two-dimensional canopy model.3.Based on the shortcomings of the existing one-dimensional urban canopy model,five improvements are proposed through theoretical derivation.At the same time,combined with the research results in 1 and 2,a quasi-two-dimensional atmospheric dynamic urban canopy model(UDC-nu)suitable for the height of non-uniform building complex was constructed.Experiments verify that the model is basically reliable and the calculation results are highly accurate.UDC-nu can be used for dynamic simulation calculation of wind and thermal environment of highly non-uniform building groups,providing a prerequisite for the follow-up study in 4.4.Using the UDC-nu model established in 3,through single-factor numerical experiments and multi-factor orthogonal experiments,the effects of building height,building density,building height dispersion and other factors on the wind and thermal environment of urban residential areas under different weather conditions are studied.The effect of human comfort.The optimal solutions for improving the natural ventilation capacity of residential areas and improving the comfort of pedestrians in residential areas are given,respectively,and targeted to improve outdoor wind in urban residential areas.Thermal environment strategy.