Numerical Modeling For The Building Performance Of City Underlying Surface And Thermal Environments In WuHan

With the rapid development of the process of urbanization, Great changes have been made in city underlying surface. It is a problem that attracts recearchers' attention.However ,the lack quantification study for a long term ,including that how plant affect the city underlying surface,how the city underlying surface affect building wind environment, and how to solve it,also the lack advisable Prediction Methods,and Study on the methods of improving civic thermal environment which was caused by the variation of city underlying surface, In order to solve these problems,some studies are carried out in this thesis.Firstly,taking advantage of computational fluid dynamics which could generate unstructured grid and couple models for natural ventilation and radiation ,making research more Predictive and quantificative.Secondly, a general 3-D radiation simulation system is developed, which could realize an accurate radiation calculation with using which the short-wave and long-wave transmission processes inside the canopy of plant, including reflection, absorbsion and transmission, could be predicted accurately. The models contains DO radiation model,Air model ,Planting model, Longwave radiation and Shortwave Terrain model, Boundary model and Architecture model.Calulate theheat - balancing on architecture surface with the mothed of finite difference .Obtaining hourly air temperature on architecture surface and quantitative simulating results.Thirdly, condition of underlying surface without vegetation is continuingly analyzed and compared with the result that of having vegetation. What's more, relationship among reflectivity and rate of evaporation of underlying surface and city thermal environment is studied though abundant digital tests. The result shows that the way of enhancing the reflectivity of underlying surface to improve the thermal environment outside is not always effective. High rate of reflectivity can low down the temperature of underlying surface and then low down the temperature of air. Nonetheless, the enhancing of the rate of reflectivity can also result in the rising of average radiation temperature and person's thermal comfort feeling don't have effective improve and even slow down.Fourthly, the relationship between underlying building surface and thermal environment is simulated and studied. Comparative comfort's evaluating standard is introduced in and city's wind environment is simulated and settlement is brought foreword.At last, appropriate using of solar energy is advanced to improve city thermal environment and save energy. Using the climate qualification of Wuhan, feasible project is simulated and analyzed.