| Project/Area Number |
20300207
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Sports science
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| Research Institution | University of Tsukuba |
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Principal Investigator |
ASAI Takeshi University of Tsukuba, 大学院・人間総合科学研究科, 教授 (00167868)
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| Co-Investigator(Kenkyū-buntansha) |
SEO Kazuya 山形大学, 地域教育文化学部, 准教授 (60292405)
HUJII Norihisa 筑波大学, 大学院・人間総合科学研究科, 准教授 (10261786)
TAKAGI Hideki 筑波大学, 大学院・人間総合科学研究科, 准教授 (80226753)
KOIKE Sekiya 筑波大学, 大学院・人間総合科学研究科, 准教授 (50272670)
HUJISAWA Nobuyuki 新潟大学, 工学部, 教授 (20165369)
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| Project Period (FY) |
2008 – 2010
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| Project Status |
Completed (Fiscal Year 2010)
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| Budget Amount *help |
¥10,400,000 (Direct Cost: ¥8,000,000、Indirect Cost: ¥2,400,000)
Fiscal Year 2010: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2009: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2008: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
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| Keywords | 流体 / ボール / 空力 / 抵抗 / 回転 / サッカー / バレー / 渦 / 不安定性 / 臨界 / 乱流 |
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| Research Abstract |
In this study, to analyze the knuckling effect of a soccer ball in actual flight, the characteristics of the unsteady wake structure were experimentally investigated by using high-speed video images and a smoke-generating agent. The experimental data indicate that the frequency of fluctuation of lift and side forces and the frequency of wake oscillation are closely related to each other with a statistically high correlation (r=0.94, p<0.01). From these results, the present study concludes that the phenomenon of large-scale vortex undulation in the wake is caused by the unsteady characteristics of the lift and side forces acting on a knuckleball, which might be related with the extraordinary instability in the separation of boundary layers.
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