| Project/Area Number |
12650159
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | Niigata University |
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Principal Investigator |
NARUMI Takatsune Faculty of Engineering, Niigata University, Associate Professor, 工学部, 助教授 (20143753)
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| Co-Investigator(Kenkyū-buntansha) |
TOGA Shinji Toyama National College of Maritime Technology, Lecturer, 電子制御工学科, 講師 (90270248)
HASEGAWA Tomiichi Faculty of Engineering, Niigata University, Professor, 工学部, 教授 (80016592)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2001: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2000: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | Suspension / Colloidal Dispersion / Shear Induced Structure / Memory Effect / Functional Fluid |
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| Research Abstract |
We have investigated the flow-induced structures of suspension and colloidal systems and those influence on the flow characteristics, relating to the application as the functional fluids.
In the first test with concentrated suspensions, we had concerned with the rearrangement process of the particle structure after a shear reversal in oscillatory flow with large strain. Regardless of the shear rate applied, the process was a solid like behavior because it was only depended on the strain. The apparent viscosity estimated in the quasi-steady oscillatory flow after the transient period was affected with the unsteadiness. That is, the apparent fluidity was increased in high frequency conditions and this tendency was conspicuously observed in the mono-dispersed systems. Moreover, the dependency of the viscosity evaluated in the oscillatory flow on the rate of the volume fraction in bi-disperse systems was remarkably different with that obtained in steady flow.
In the squeezing test of the concentrated suspensions, we had found that the apparent yield stress, that is solid like property, was increased with the reciprocated squeezing motion. The results obtained with the different conditions in squeezing velocity, particle shape and so on show that the concentration and the stronger cohesive structure was generated at the center region of squeezing flow due to the filtration effects
In the test of colloidal systems, we have experimentally studied the dilute colloidal dispersion of the fine polystystyrene spheres passing through a small orifice, where it was obtained that the colloidal particles gave a stability or an instability effect on the orifice flow depending on the electrolyte density. This measured flow rates fluctuated with strong electrostatic repulsion. The increase in the electrolyte density stabilized the orifice flow, whereas excessively high electrolyte density caused instability in the flow rates.
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