2004 Fiscal Year Final Research Report Summary
Wind tunnel experiments about transfer coefficient in urban surfaces and modeling of city structure.
| Project/Area Number |
15560516
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Architectural environment/equipment
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| Research Institution | Nippon Institute of Technology |
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Principal Investigator |
NARITA Ken-ichi Nippon Institute of Technology, Department of Architecture, Professor, 工学部, 教授 (20189210)
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| Project Period (FY) |
2003 – 2004
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| Keywords | heat island / heat budget / sensible heat flux / transfer velocity / convective heat transfer / wind tunnel experiment / urban canopy / turbulence |
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| Research Abstract |
The modeling of convective heat flux in urban area is one of the important problems in heat island study. In this paper, the distribution of convective transfer coefficient within urban canyon is investigated using our originally devised "water evaporation technique". The merit of this technique is to measure the convective flux precisely, in comparison with similar experiments about heat flux. Besides, we can easily restrict the flux in an arbitrary surface or even the portion within the surface.
The main topic in this study is the effect of canyon geometry about three-dimensional cubic array. The vertical distributions of convective transfer coefficient were measured in various densities and its change due to wind direction was also examined. The variation of coefficient within same surface is not negligible, that means, if constant value assumed for all position it leads to considerable error in some case. Another topic is the effect of roof shape on convective transfer coefficient. The two-dimensional models with gable roof (inclination from flat to 65.4 degree) were used in experiments. The distributions of coefficient were revealed in all kind of model surface and street surface between models.
Though these experiments about cyclic regular arrangement give fundamental information for modeling of urban structure, we have to check whether such a simplified arrangement is considered as a representative of actual city. Therefore, we also measure the distribution along a street of real existed city model using same water evaporation technique. The difference among points within the same street is remarkable, and maximum value exceed twice of minimum point. As convective transfer coefficient is closely related with wind speed or diffusion ability, it can be considered that these results are also representative of ventilation rate in each position.
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Research Products
(12 results)
