The Digital Research On Wind Environment Of The Near Surface Layer In The Mountainous City

The accelerated process of urbanization and excessive expansion of urban result in the contradiction between man and nature. In China, Mountainous area accounts for more than 60%, the mountainous area has become the main source of the city, and the mountainous city has become the main form of urban development.Because of the complex landform of mountain city, it is so difficult to plan, it can't merely follow the plain city. In order to achieve the best use of mountain settlements,the urban planning workers are committed to exploring a suitable planning and construction method of mountain city for a long time.City surface layer is the main area of human existence, the environment of surface layer is closely related to human living comfort. In recent years, the urban problems have become increasingly prominent, people are concerned about the quality of the city's wind environment. has beem an important standard to measure the quality of the environment of the city. The near surface wind environment has become an important standard to measure the urban environment.The planners need the macro-control of wind environment in urban planning, the current basic data of the wind environment are derived from local meteorological bureau.But the mountains and rivers staggered and complex landform greatly influence the characteristics of wind environment, it is too simple to use meteorological bureau data to plan the mountain city. Therefore, at the beginning of the planning and construction of the mountainous cityin,it has a very important practical significance to establish a scientific and effective wind environment research system to obtain the surface wind environment data of the planning area. In view of the above problems, this paper has carried out the following research.(1) After reading a lot of literature and research status of urban ventilation method and urban wind environment, the author find the current research on the outdoor wind environment of the large scale mountainous city is few. Because of the complex terrain, when the numerical simulation technology applied to the study of the wind environment in mountainous city,the main technical problem is how to build the model of a large area of terrain. At present,it lack of the technology of 3D modeling for complex terrain and a reliable, scientific and systematic research system for the mountain wind environment.(2) The author has summarized the local circulation characteristics in the mountainous area.By the analysis of the actual test data, the author found that the wind velocity and wind direction are relatively large between the foot measuring point and top measuring point of a same mountain, the distribution of wind velocity is closely related to altitude.Terrain has great influence on the mountain wind environment,but it is so less on area with small undulation of topography and the urban layout is often the main influencing factor.By the summary of the theory of wind environment evaluation, the author proposed the wind velocity zoning method for the macro grasp of overall urban wind environment.(3) Introduced the basic theory and method of numerical simulation technology and the geographic information system and digital elevation model, proposed a convenient and fast digital modeling method for complex topography of mountainous region. By data formats conversion to achieve the convergence between the various digital technologies, the author established a scientific, reliable and systematic digital research system suitable for mountain wind environment in this paper.(4) Established CFD model by the digital modeling method in this paper, use numerical simulation technology researsh the characteristics of winter and summer wind environment in Qijiang with the background wind velocity so that planner got the basic data of whole wind environment in the early planning and Determination of the wind velocity in the study area by the method of wind velocity, put forward planning proposal for building layout in the area of each wind velocity.(5) Described the ventilation corridor concept and its manifestations, established the model with the urban space as subject including urban main road, secondary road, green belts, rivers, buildings by Sketch up, used CFD numerical simulation technology to researsh the wind velocity distribution of ventilation corridor and feedback it to ventilation corridor planning,put forward the generalized ventilation corridors. Using the specific planning case, analysis the construction of the corridor under the guidance of the overall wind environment from the regional planning, urban planning, district planning level.According to the construction of Urban Ventilation corridor, put forward the design strategy of the wind environment in mountainous area.