| Project/Area Number |
03555118
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Hydraulic engineering
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| Research Institution | Kobe University |
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Principal Investigator |
KANDA Tohru Kobe University, Department of Civil Engineering, Professor, 工学部, 教授 (30029144)
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| Co-Investigator(Kenkyū-buntansha) |
中辻 啓二 大阪大学, 工学部, 助教授 (10029324)
MURAOKA Kohji Osaka University, Department of Civil Engineering, Professor, 工学部, 教授 (90029017)
MICHIOKU Kohji Kobe University, Department of Civil Engineering, Assco. Prof., 工学部, 助教授 (40127303)
YANO Motoaki Kobe University, Department of Civil Engineering, Professor, 工学部, 教授 (80031061)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 1992: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1991: ¥4,800,000 (Direct Cost: ¥4,800,000)
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| Keywords | Reservoir Dynamics / Field Survey / Density Currents / Water Quality / Environment / Numerical Model / Artificial Control / Circulation / Water Quality / Density Current / Thermal Stratification / Mixing / Temperature Measurement / Turbulence / Circulation |
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| Research Abstract |
The results obtained in the present research program are briefly summarized as follows.
Kanda experimentally examined the water quality improvement by pumping up the bottom layer fluid and showering it to the water surface from above. He devised a physical model system in order to simulate such a situation. By using salt and fresh waters as working fluids. Kinematic and dynamic behaviors of the plunging fluid mass are carefully examined. Based on a dimensional argument, dimensionless parameters governing water mass dynamics are obtained. Mixing and diffusion processes of water mass are analyzed by using these parameters. Based on the experimental results he proposed empirical formulas for predicting water quality transportation which is applicable to the phenomena in prototype reservoirs.
Yano made laboratory experiment to investigate high efficiency of water improvement operation by discharging the surface water onto thermocline interface. We term this method "internal circulating opera
… More
tion". The bottom layer fluid is entrained across the thermocline due to penetration and rebound of discharging fluid. He experimentally obtained an entrainment relationship in this system. Applying the entrainment law and taking momentum and mass conservation principles into consideration, he constructs a analytical model to predict water quality variation sue to the internal circulating operation.
Michioku carried out a field survey of internal wave motion in a stratified reservoir to examine their dynamics under the wind action on water surface. Stochastic analysis on internal behaviors in the stratified water body is performed to find out relationship between wind shear mechanism and internal wave reaction. A theoretical consideration based on the internal wave dynamics is also made to describe the internal wave motions. The observed modal structure and stochastic properties of wave fields are successfully reproduced by our analysis.
Muraoka examined the role of wind shear stress on water quality behaviors by making a laboratory experiment in by means of an open channel installed in a wind tunnel. He found dynamics of the thermocline setting up motion, the resultant upwelling of bottom water and the vertical entrainment process. Also performed is a feasibility study to construct coastal structures to control the wind stress action on the impounded water behaviors so that the water quality can artificially be controlled.
Nakatsuji formulated a three dimensional numerical model the water mass and quality beahviors. His model is applicable to water bodise with complicated three dimensional lake bottom geography. He verified the model by making case studies in which water dynamics and qualities in clased bays and inland waters are successfully predicted. He also devised a visualization technique of the numerical results so that we could easily understand hydraulic behaviors of water quality factors. Less
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