A Novel Type of Instability due to Hyperbolic Instability and Phase Shift by Waves
| Project/Area Number |
17K05561
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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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| Research Field |
Mathematical physics/Fundamental condensed matter physics
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| Research Institution | Tohoku University |
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Principal Investigator |
Hattori Yuji 東北大学, 流体科学研究所, 教授 (70261469)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2017: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | 双曲型不安定性 / 密度成層 / 自転効果 / 電磁流体 / 内部重力波 / アルヴェーン波 / 渦列 / 非線形挙動 / 流体 / 気象学 / 応用数学 |
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| Outline of Final Research Achievements |
The vortices which appear in a wide variety of flows often possess hyperbolic stagnation points. It is shown that there appears a new type of instability due to the hyperbolic instability and phase shift by waves in the vortices which possess hyperbolic stagnation points affected by density stratification, rotation, or magnetic field. The physical mechanism of this instability is revealed. Characteristics of stability including the condition of instability are also revealed. Combined effects of density stratification and rotation are elucidated. The role of the new instability in turbulent transition is clarified by numerical simulation.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究では、気象現象・惑星大気・宇宙流体現象において重要である密度成層・回転・磁場の効果により、これまで知られていなかった流れの不安定性が発現することを明らかにした。これは、台風や竜巻の挙動・進路/成長予測の精度向上を図る上で考慮する必要があるもので、これに貢献することができる。また、長年の課題である木星の長寿命渦の維持メカニズムの解明の突破口となる結果を得た。さらに、既知の不安定性（双曲型不安定性）に別の現象（波動）が作用することで生み出される複合的な不安定性の概念は、今後流れの安定性理論の新しい分野を拓くと期待される。
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Report
(4 results)
Research Products
(21 results)
