1999 Fiscal Year Final Research Report Summary
Studies on elucidation of the air-water gas transfer mechanism on the surface of breakers and the modeling of it
| Project/Area Number |
10450185
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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 |
水工水理学
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| Research Institution | Osaka City University |
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Principal Investigator |
KAKUNO Shohachi Faculty of Engineering, Professor, 工学部, 教授 (70047398)
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| Co-Investigator(Kenkyū-buntansha) |
SUGIHARA Yuji Interdisciplinary Graduate School of Engrg. Sciences, Kyushu Univ., Research Associate, 大学院・総合理工学研究院, 助手 (70243970)
ETOH Goji Faculty of Science and Engrg., Kinki Univ., Professor, 理工学部, 教授 (20088412)
ASAI Koji Faculty of Engineering, Yamaguchi Univ., Assistant Prof., 工学部, 講師 (70202570)
HOSOI Yoshihiko Faculty of Engineering, Tottori Univ., Professor, 工学部, 教授 (50127859)
NAKAMURA Yoshiyuki Marine Environment Division, Senior Researcher Port and Harbor Research Institute, Ministry of Transportation, 海水浄化研究室, 室長 (90172460)
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| Project Period (FY) |
1998 – 1999
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| Keywords | bubble / gas transfer / breaker / global warming / PTV / wind waves / turbulence by oscillating grid / microelectrode |
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| Research Abstract |
・By visualizing breaker image taken by a special video camera, the relation between bubble characteristics and wave characteristic in the breaker zone was analyzed.
・The model formula of gas transfer velocity taking the effect of the entrained bubble in the breaker zone was proposed.
・An image analysis technology with high-accuracy for measurement of the flow field in the breaker zone was developed.
・Applying the laser induced fluorescence, the visualization of the entrainemnet process of CO_2 gas into the water-phase was succeeded.
・It was found that the penetration depth of entrained bubbles of the plunging breakers is deeper than that of the spilling breakers.
・It was found that the swell in the wind-waves promotes the gas transfer and that the effect of it becomes big as the wave period becomes shorter.
・Gas transfer velocity at the water surface under the condition of the vibrating grating turbulent flow field was evaluated. The velocity was found to be controlled by the Large Eddy Model.
・Distribution and change of CO_2 and N_2O on the subtropical equator of the Pacific Ocean were clarified.
・The modeling of the gas exchange process for the bubbles entrained in the breaker zone was made, and the validity was verified from an experiment under the condition of a single bubble.
・It was succeeded to visualize the entrainmenet process of bubbles into water by the breakers from the results of bubble observation in the field using ultrasonic wave and video image shot simultaneously.
・State of the art on the studies of air-water gas transfer phenomenon was investigated through the literature.
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