| Project/Area Number |
02650355
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Hydraulic engineering
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| Research Institution | Nagaoka University of Technology |
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Principal Investigator |
FUKUSHIMA Yusuke Nagaoka University of Technology Department of Civil Engineering Associate Professor, 工学部, 助教授 (40111661)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Yoshiyuki Nagaoka University of Technology Department of Civil Engineering Research Associ, 工学部, 助手 (90172460)
HAYAKAWA Norio Nagaoka University of Technology Department of Civil Engineering Professor, 工学部, 教授 (70143815)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1991: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1990: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | Density underflow / Density front / Turbulence model / Numerical analysis / 下層密度流 / フロント |
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| Research Abstract |
The purpose of this study is to analyze the front of density underflow using the k-epsilon turbulence model. First, in order to investigate the turbulence structure of the front of the density underflow and the mechanism of the entrainment by the front, the experiments are carried out. The angle of the bed slope is chosen as a parameter. The salt water flows into the body of the fresh water filled in the tank to form the density front. The velocity distributions in the density front are measured by the hydrogen bubble method. The concentration distributions of salinity in the front are measured by the conductivity meter. From these experiments, the properties of the distributions of the velocity and the concentration in the density front are clarified in comparison with the characteristics of the steady region of the density underflow.
Next, the method of the unsteady numerical analysis using k-epsilon turbulence model is developed. The model consists of the following basic equations :
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the mass conservation equation of the fresh water, the conservation equation of the salinity concentration, the momentum equation, the equation of the kinetic energy of turbulence and the equation of the viscous dissipation rate of the turbulence. The numerical analysis model adopts the volume integral method to discretize the basic equations. This method is numerically stable in comparison with the other method.
The preliminary calculations are carried out to test the present model of the numerical analysis. The target of the calculation is the steady region of the density underflow. The results are compared with the experimental data. The present model explains well the characteristics of velocity and concentration distributions of the density underflow.
The present model is applied to the analysis of the front of the density underflow in which the flow is essentially unsteady. The distributions of the velocity and concentration of the aslinity and the interface of the density front are calculated. The flow mechanism of the unsteady density front is explained well by the present analysis. Less
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