| Project/Area Number |
02455016
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
広領域
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
KOMORI Satoru KYUSHU UNIV.,DEPT.OF.CHEM.ENG.,ASSO.PROF., 工学部, 助教授 (60127082)
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| Co-Investigator(Kenkyū-buntansha) |
UEDA Hiromasa KYUSHU UNIV.,APPLIED MECH.INSTI.,PROF., 応用力学研究所, 教授 (70026186)
NAKAMURA Yasuharu KYUSHU UNIV.,APPLIED MECH.INSTI.,PROF., 応用力学研究所, 教授 (80038554)
神崎 隆男 九州大学, 工学部, 助手 (30221906)
天田 次雄 九州大学, 工学部, 助手 (10180093)
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| Project Period (FY) |
1990 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥7,200,000 (Direct Cost: ¥7,200,000)
Fiscal Year 1992: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1991: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1990: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Keywords | GLOBAL WARMING / AIR-SEA INTERFACE / CARBON DIOXIDE EXCHANGE / GAS-LIQUID INTERFACE / TURBULENCE STRUCTURE / 炭酸ガス吸収 |
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| Research Abstract |
The mass transfer mechanism across a sheared air-water interface without bubble entrainment due to wave breaking was experimentally investigated in terms of the turbulence structure of the organized motions in the interfacial region in a wind-wave tank. The transfer velocity of the carbon dioxide (CO_2) on the water side was measured through reaeration experiments of CO_2, and the fluid velocities in the air and water flows were measured using both a hot-wire anemometer and a laser-Doppler velocimeter. The results show that the mass transfer across a sheared air-water interface is more intensively promoted in wind shear, compared to an unsheared interface. However, the effect of the wind shear on the mass transfer tends to saturate in the high-shear region in the present wind-wave tank, where the increasing rate of mass transfer velocity with the wind shear decreases rapidly. The effect of the wind shear on the mass transfer can be well explained on the basis of the turbulence structure near the air-water interface. That is, surface-renewal eddies are induced on the water side through the high wind shear on the air-water interface by the strong organized motion generated in the air flow above the interface, and the renewal eddies control the mass transfer across a sheared interface. The mass transfer velocity is correlated with the frequency of the appearance of the surface-renewal eddies, as it is in open-channel flows with unsheared interfaces, and it increases approximately in proportion to the root of the surface-renewal frequency. The surface-renewal frequency increases with increasing the wind shear, but for high shear the rate of increase slows. This results in the saturated effect of the wind shear on the mass transfer in the high-shear region in the present wind-wave tank. The mass transfer velocity can be well estimated by the surface-renewal eddy-cell model based on the concept of the time fraction when the surface renewal occurs.
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