| Project/Area Number |
05640440
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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 |
物性一般(含基礎論)
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| Research Institution | Fukui University |
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Principal Investigator |
OHTSUKI Toshiya Fukui University, Department of Applied Physics, Associate Professor, 工学部, 助教授 (10203845)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Mitsuya Fukui University, Department of Applied Physics, Assistant, 工学部, 教務職員 (40227179)
IWATA Kazuyoshi Fukui University, Department of Applied Physics, Professor, 工学部, 教授 (00020230)
HAYASHI Akihisa Fukui University, Department of Applied Physics, Associate Professor, 工学部, 助教授 (80208610)
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1994: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1993: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | Molecular Dynamics / Granular Material / Segregation |
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| Research Abstract |
Segregation by shaking in cohesionless granular materials was investigated by Molecular Dynamics simulations, where granular particles are modeled by inelastic hard discs. Temporal evolution of the height h of one tagged particle immersed in a set of monodisperse particles was pursued for various values of the particle size and density. It becomes evident that even a particle denser than surrounding particles goes up. The existence of the steady state independent of of initial conditons is also elucidated. The height h_* at the steady state is a continuously varying function of the particle size and density. With increasing size, h_* reaches a maximum after rapid increase, whereas h_* decreases with increasing density.
In these calculations, periodic boundary conditions were adopted for right and left sides of the system. Recently, it has been reported that when confined into a narrow cylindrical column, the large particle is carried to the top by the upward convection and trapped there because the width of downward convection is too thin to carry back the particle. Then we carried out simulations for both periodic and solid boundaries and compared results. In the case of solid boundaries, convection takes place and exerts serious influence on the tagged particle motion. In the case of periodic boundaries, oppositely, convection is not observed and is irrelevant to the particle motion. It follows that the system size dependence of h_* is qualitatively different in both cases. It is concluded that segregation is ascribed by at least two mechanisms. One is global convection, where surrounding particle behave like a fluid-like continuum. The other is a microscopic mechanism, where the system shows discrete particle-like behavior.
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