2002 Fiscal Year Final Research Report Summary
Study on Current and Mass transfer at the Middle and Large Depth of Ocean by Hydraulic Model Test and Numerical Simulation
| Project/Area Number |
12305066
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
海洋工学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SATO Toru Graduate School of Engineering, Associate Professor, 大学院・工学系研究科, 助教授 (30282677)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Hideyuki Graduate School of Engineering, Associate Professor, 大学院・工学系研究科, 助教授 (00196859)
YAMAGUCHI Hajime Graduate School of Engineering, Professor, 大学院・工学系研究科, 教授 (20166622)
MIYATA Hideki Graduate School of Engineering, Professor, 大学院・工学系研究科, 教授 (70111474)
KYOZUKA Yusaku Kyushu University, Interdisciplinary Graduate School of Engineering Sciences, Professor, 大学院・総合理工学環, 教授 (80177948)
BABA Nobuhiro Osaka Prefecture University, Graduate School of Engineering, Associate Professor, 大学院・工学系研究科, 助教授 (10198947)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Ocean Current Model / Rotational Tank / Hydraulic Model / Density Current / Stratification / Coriolis Force / Ariake Bay / Isahaya Inlet |
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| Research Abstract |
Mechanisms in the mass transfer in the ocean including density current were elucidated numerically and experimentally.
Firstly, a numerical simulation code for the spatial scale of closed bays was developed. One of the special features of this model is the combination of a full- 3-D model and a hydrostatic-pressure appropriation model. This was applied to investigate the effect of water-purification by using density current in Gokasho Bay, Mie Prefecture. Its results are in qualitatively good agreement with the observation. Then, a hydrostatic model of the bay was installed in the rotational tank The spread of dye was examined by the luminance method and gives similar results with the calculation.
Next, experiments for observing the effect of the Coriolis force on density current was carried out in a smal I circular tank of the diameter of 1m, set in the above-mentioned rotating tank. It was found that the spread of density current is explained by an appropriate non-dimensionalisation, when no rotation. It is also observed that the rotation suppresses the spread and, as the Rossby number becomes small (the rotation increases), a break-up of the dye spread occurs. Our 3D CFD simulation gave similar results.
Lastly, the hydrographical change by the existence of the Isahaya dyke was examined. It was shown by the model test that the residual current in Isahaya Inlet abates by the installation of the dyke to a significant extent. This may attenuate the water exchange in the inlet and give a chance to red tide growth. Also observed is that the current change at the mouth of the inlet push the nutrients supplied by Chikugo River away from the seaweed cultivation fields in the northwest of Ariake Bay. This may also cause the damage.
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