To analyze the thermal effect of urban green areas, both measurement and simulation are necessary because it is impossible to get enough information from the limited numbers of measurements for such a broad area and time dependent phenomenon. In this study, a simulation model for analysis of the thermal effect of urban green areas was developed. As the temperature and surface roughness rapidly change near the urban green area, a turbulent simulation model which can simulate an abrupt change of diffusivity should be used for the simulation. The
k-ε two equation model, one of the simulation methods for turbulent phenomena, was used in this study. The details of the scheme of the model and boundary conditions are explained.
For validation of the model, wind tunnel experiments and a measurement were compared with the result of the model.
The first set of wind tunnel experiments was a “pulse change of surface roughness”, where the surface roughness was changed from smooth to rough, then smooth again. The second case was a “pulse change of surface temperature”, where the surface temperature was changed from cool to hot, then back to cool.
The measurements of Katayama
et al. (1987), a rare set of measurements that include the profile of wind velocity, temperature and humidity around a pond in an urban area, was used in this study to validate the model.
The results of the wind tunnel experiments and the measurements were compared with the calculations of the model and generally showed good agreement with the results of the simulations.
These results indicate that it is possible to use the simulation model for the analysis of the thermal effect of urban green areas.
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