基于数值模拟的城市中心区风环境研究

Numerical simulation of wind environment in the urban areas

利用CFD软件对长沙市中心区典型区域的风环境进行了三维数值模拟研究。结果表明,城市建筑群布局不当会造成多方面不利影响:如建筑群内局部地区气流不畅,污染物难以扩散,影响市民身体健康;街道峡谷风使得行人行动不便,冬季热舒适感差;复杂的风环境可能造成建筑构件的损坏乃至脱落,对地面行人的安全造成威胁;建筑围护结构渗透风增加造成建筑能耗的增加。在城市规划和建设中,中心区风环境状况要引起足够的重视,在建设之前要进行风环境模拟与评估。

In this paper,we would like to introduce a numerical simulated model of a typical area of City Changsha established based on the real data statistics made by the corresponding departments.As we know from our daily experience,the wind environment has been becoming more and more complicated as a result of setting up more and more high-rises.To some extent,it has made our urban living environment more and more unpredictable with the consequence unknown.The situation has pushed us to accomplish our 3-dimensional numerical study of the wind environment by means of computational fluid dynamics software. The results of our simulation help us to disclose the fact that unreasonable layout of the architectural complex has a harmful effect in many ways.As it can be seen,the wind flow of some areas in the architectural complex is sluggish due to circuitous and narrow streets,and diffusion of contaminants becomes more and more serious.With the ever increasing concentration of the high-rises,the velocity of the wind becomes higher due to the serious reduction of the wind-flowing space.In some areas of narrow streets,when the wind flows into the streets, the high blowing velocity of the wind has resulted in the street-canyon wind,which makes the pedestrians on the streets feel unpleasant and discomfort particularly in the cold winter days.There would also suddenly appear strong surface stress of the wind on the areas with clusters of high-rises the urban areas concentrated with high-rise building clusters.In addition,if the architects fail to pay enough attention to the variation of weather change and the wind-flowing directions,negative pressure effect would become more serious than what the architects would have expected（e.g.the effect on the glass curtain wall,and billboard）,which tends to bring damage and even high-rise would fall off and cause disastrous consequences and even threaten the safety of the local pedestrians.In addition,more outdoor blowing wind（which is hotter in summer and colder in winter） infiltrating into the room through the building envelopes would increase the energy consumption due to the differential pressure changes to the front and the back of the high-rise buildings in the street canyon.Therefore,it is strongly recommended to take more thoughts when planning of new urban areas,which can be shown in our simulation to the wind environment of the architectural complicated situations.