| Project/Area Number |
11450388
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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 |
海洋工学
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| Research Institution | Osaka University |
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Principal Investigator |
SUZUKI Toshio Osaka University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (80029107)
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| Co-Investigator(Kenkyū-buntansha) |
TAKEMI Tetuya Osaka University, Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (10314361)
SUZUKI Hiroyoshi Osaka University, Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (00252601)
TODA Yasuyuki Osaka University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (20172166)
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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 |
¥12,600,000 (Direct Cost: ¥12,600,000)
Fiscal Year 2001: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2000: ¥4,900,000 (Direct Cost: ¥4,900,000)
Fiscal Year 1999: ¥4,800,000 (Direct Cost: ¥4,800,000)
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| Keywords | Density current / flow visualization / tidal current in bays / PIV / upwelling / MEG model / boundary fitted coordinates grid / 中性浮遊粒子 / シャドウグラフ / 適合座標系 |
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| Research Abstract |
Objectives of this research work are to clarify the mechanism of large-scale turbulent structure, which occurs at vertical mixing process in density current, and to develop the numerical simulating method. Experimental measurements in three-dimensional density stratified water tank, tidal current data Ohmura-bay and atmospheric weather and ocean data obtained by Ocean observation ship "MIRAI" are used to compare with the numerical simulated results.
Obtained results are as follows,
(1) Measurement technique for density current using neutral density particles in two layers is developed and measured velocity distributions give good agreement with the calculated results.
(2) Front-end speed of the density current does not include strong mixture turbulence, but separations are occurred at the rear part of front nose. The turbulence at that separated regions are significant.
(3) Density mixing phenomena is strongly affected by the separation, which occurs at the behind of bottom bank.
(4) Density stratified stable layer prevents upwelling mixing, especially the upwelling by vortex pair cannot break the large density jump layer.
(5) Mixing process by surface cooling is simulated by numerically and it is clarified that the birth of small-scale plumes are the origin of the density mixing.
(6) Numerical simulator "MEG model" is modified to the boundary fitted coordinates grid and the flow pattern is calculated in the Omura-Bay area. Results show good agreement with the measured tidal data. The availability of this scheme is confirmed.
(7) Atmospheric density current velocity is evaluated by cloud movement. The results are compared with data of radiosonde. It shows that the cloud movement velocity is almost coinciding with the atmospheric velocity distribution in the convection layer. The facts that there is a stratified layer when the convective activity is in depressed period, but no layer in the active period.
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