Numerical Simulation For Urban Settlements Outdoor Thermal Environment

This paper attempts to use CFD techniques to processing fine simulation study of thermal environment of settlements in the outdoor with the previous basis, and use quantitative analysis of the relationship between the different influence factors and the form of the architectural layout and the thermal environment of urban settlements, the article focuses on the following areas:First of all, the article explains that the background to the study, purpose, meaning, and the rapid growth of urban population has led to the rapid expansion of housing demand, and the construction of settlements gets development, this trend is not only to make a wide range deterioration of the thermal environment of the city, so the research of the urban heat environment have a guiding role to reduce the heat island intensity in the district, optimizing the thermal environment in the district. improve the thermal comfort of residents, save the building energy consumption and give future planning of settlements,.Secondly, the article introduces numerical simulation software and theory of the thermal environment of the settlements. This study uses CFD technology to study on air flow modeling and prediction of the buildings'outside, describing the process of solving the general computational fluid dynamics in detail, and list the corresponding parameters for the use of simulation, to provide theoretical support for the following specific operations.Thirdly, by choosing the combining method of vertical and horizontal synchronous observations, the outdoor surface temperature, underlying surface and near wall temperature were observed in a high-rise residential complex located on the west of Hangzhou in summer 2009, and three-dimensional distribution of high-rise residential outdoor thermal environment was analyzed. Results show that there is a big difference in 3D distribution regularity of outdoor thermal environment for high-rise buildings in different directions at different hours under the condition of static or breeze. In vertical direction, the near wall temperatures of eastern and southern wall peak at 12:00 from the 2nd to the 18th floor, while the western and northern near wall temperatures reach to a peak at about 14:00 pm. In a horizontal direction, the surface temperature and underlying surface temperature are not only related to the underlying characteristics, but also affected by building shade. The results could provide a scientific basis for the energy-saving planning and design and promote low-carbon and ecological high-rise residence area developing in hot summer and cold winter zone in China.Last, using three types of urban residential in the west of Hangzhou as simulation area, this study simulated the three-dimensional distribution of the outdoor building thermal environment with horizontal and vertical outdoor observed temperature data and CFD technique. Two scenarios were considered when comparing the breeze or calm wind condition:one with the heat conductivity and the other with both heat conductivity and natural convection case. The present paper aims at using different types of settlements to examine the spatial distribution of the outdoor thermal environment. The result showed that the outdoor settlements thermal environment is influenced by settlements underlying surface distribution, solar radiation and thermo physical properties of the buildings surface and many other factors, taking into account the heat conductivity and natural convection conditions, which is closer to reality than only considering the heat conductivity conditions. In similar circumstances underlying surface distribution, solar radiation and thermo physical properties of the buildings surface, the ratio of horizontal distance buildings and building height is smaller, the interference between heat sources is more frequently and the air temperature between buildings is higher. When the height of the vertical direction changes, the factors transform from underlying surface thermal to solar radiation and natural convection effects. The point-high building construction layout of the outdoor thermal environment is better than enclosed multi-level layout and the determinant settlements.