Heat flux measurement of urban boundary layers in kyoto city and its prediction by cfd simulation

In   the   summer   of   2002,   measurements   were simultaneously performed to investigate the characteristics of heat flow in urban areas at three locations in Kyoto city: 1) a commercial urban area mixed with low-rise traditional residential buildings that represents the urban area of Kyoto, 2) an university campus area with a lot of green zones, and 3) a plaza covered with a concrete slab which was used as a reference point of measurement. Heat flux of boundary layer over the three locations and the surface temperatures of building walls and streets were measured to investigate the urban thermal environment. For the analysis, a new simulation code was developed by combining unsteady state heat conduction of building walls and grounds, radiation heat exchange between them, and airflow by CFD (Computational Fluid Dynamics). By using this code, the thermal environment of the urban areas such as air temperature, humidity, wind velocity, and boundary layer heat flux was predicted and compared with the measured results. It was found that this model could predict the real thermal environment of the urban area. Using this code, the effect of additional green on roofs and grounds can be investigated in order to mitigate urban  heat  island  and  to  improve  urban  thermal environment at the street level.