| Project/Area Number |
17560166
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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 |
Fluid engineering
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| Research Institution | Tokyo University of Science |
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Principal Investigator |
KAWAGUCHI Yasuo Tokyo University of Science, Faculty of Science and Technology, Professor (20356835)
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| Co-Investigator(Kenkyū-buntansha) |
KAWAMURA Hiroshi Tokyo University of Science, Faculty of Science and Technology, Professor (80204783)
SEGAWA Takehiko Tokyo University of Science, Advanced Institute of Industrial Science and Technology, Energy Technology Research Institute, Researcher (50357315)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,540,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥240,000)
Fiscal Year 2007: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2006: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2005: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Turbulence / Non-Newtonian Fluid / Drag Reduction / Laser Measurement / Direct Numerical Simulation / RANS model / 流体工学 / シミュレーション大学 / 省エネルギー / 乱流モデル / シミュレーション工学 |
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| Research Abstract |
It is known that the viscoelastic fluid such as dilute surfactant or polymer aqueous solution exhibits dramatic frictional drag up to 80% by turbulent suppression effect in high Reynolds number flow. In this project, the target is to develop an ensemble average model (RANS=Reynolds averaged Navier-Stokes equation) applicable to viscoelastic fluid flow.
During the investigation, detailed Laser measurement of flow was performed and spatial structure of turbulence in the drag reducing flow was captured. Increasing Reynolds number drag reduction rate once gradually increases and then decrease. This characteristic was explained from the view of turbulent structure change. Rheological properties of the drag reducing fluid were measured and they were approximated well by the Gieskus Model. Based on this constitutive equation, Direct Numerical Simulation (DNS) of turbulence were made. Budget terms composing the conservation equation of turbulence energy were evaluated. The differences from normal Newtonian fluid turbulence were clarified. In addition, it was tried to explain the drag reduction characteristics from the existence of non-effective layer near the wall.
The present study shed light to the drag reducing mechanism by additives. About the RANS model, eddy diffusivity model including the effect of relaxation time was introduced. This RANS model reproduces the result of DNS in wide range of the parameters. Therefore, this model is expected to be a useful tool for designing the high efficiency district heating/cooling system or air-conditioning system of buildings which uses drag reducing fluid.
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