| Project/Area Number |
11650231
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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 |
Thermal engineering
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| Research Institution | University of the Ryukyus |
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Principal Investigator |
NOSOKO Takehitro University of the Ryukyus, Dept. Mechanical and Systems Eng., Associate Professor, 工学部, 助教授 (80183903)
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| Co-Investigator(Kenkyū-buntansha) |
GIMA Satoru University of the Ryukyus, Dept. Mechanical and Systems Eng., Research Associate, 工学部, 助手 (60274883)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2001: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2000: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1999: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Liquid film / Falling film / Surface wave / Horseshoe-shaped vortice / Transition to turbulent flow / 表面皮 |
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| Research Abstract |
Two-dimensional waves first occur on a falling liquid film, and then they develop into the horseshoe-shaped waves holding vortices. The latter waves may have the common or similar characteristics to the horseshoe-shaped vortices arising from a viscous (laminar) sublayer in a turbulent boundary layer. In the present work, we investigated the evolution of the two-dimensional waves, the dynamics of the horseshoe-shaped waves and the associated gas absorption.
At large wave frequencies, nearly sinusoidal waves appear on the film and are decelerating as they are growing. At small frequencies, tear-drop-shaped solitary waves occur and show acceleration. Then they gradually increase the transverse disturbances and change into the horseshoe-shaped waves. At intermediate frequencies, transition from single-peaked waves to double-peaked waves and vice versa are observed.
When putting transverse disturbances of constant wavelength, λ_h on the two-dimensional solitary waves, the waves are stable to the disturbances of λ_h = 30 mm or less at small Reynolds numbers Re. The waves are unstable to the disturbances at intermediate and large Reynolds numbers, and develop into the horseshoe-shaped waves. The waves are more unstable to the transverse disturbances of shorter wavelength, and the growth rate of the disturbance increases with Re.
The transition of gas absorption of a falling film occurs at Re - 40, and the present experimental results show that the transition of gas absorption is caused by the transition from two-dimensional waves to horseshoe-shaped waves.
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