2022 Fiscal Year Final Research Report
Effect of wall roughness on turbulent structures based on mean vorticity transport equation
| Project/Area Number |
20K04274
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 19010:Fluid engineering-related
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| Research Institution | Kindai University |
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Principal Investigator |
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | 乱流 / 壁面せん断流 / PIV |
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| Outline of Final Research Achievements |
The effect of the skewness of surface roughness to mean velocity distribution in turbulent channel flow was investigated from the correlation terms of fluctuating velocity and vorticity. Karman's constant for mesh rough surface flow is lower than that for smooth surface flow, and it decreases with the skewness. The correlation terms between fluctuating velocity and vorticity are constant in the logarithmic region. The value of the correlation between the vertical fluctuating velocity and the spanwise fluctuating vorticity normalized with the wall variable for the mesh rough surface flow with the skewness of -0.847 agrees well with that for the smooth flow. The absolute value of the correlation decreases as the skewness increases. The value of the correlation between spanwise fluctuating velocity and vertical fluctuating vorticity normalized with the wall variables is positive for smooth surface flow, but negative for mesh rough surface flow regardless of the skewness.
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| Free Research Field |
流体工学
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| Academic Significance and Societal Importance of the Research Achievements |
本研究成果は，有効壁面高さ方向距離を使用した場合，粗面流における対数法則のカルマン定数の値が壁面粗度に依存する可能性を示唆するものであった．また，カルマン定数に対して，変動速度・変動渦度相関項の分布形状や符号が関係することを実験的にしたことは，学術的にも価値あるものである．対数法則に関する係数（カルマン定数を含む．）の壁面粗度に対する依存性が明らかになることによって，対数法則から導かれる抵抗則の提案に繋げることが可能となり，製品の設計への利用の観点から社会（産業界）に貢献できる．
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