2007 Fiscal Year Final Research Report Summary
Formation and Collapse of Cavity Network in a Granular Material due to Viscous Flow and Vibration
| Project/Area Number |
16540338
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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 |
Mathematical physics/Fundamental condensed matter physics
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| Research Institution | Tokyo University of Agriculture and Technology |
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Principal Investigator |
OSAMU Sano Tokyo University of Agriculture and Technology, Dept. Appl. Phys, Professor (80126292)
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| Project Period (FY) |
2004 – 2007
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| Keywords | granular material / cavity / critical stress / fluidization / landslide / buckling / bending wave / mesoscopic |
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| Research Abstract |
1. We performed experiments and found that the presence of cavity regions in an otherwise uniform granular material gives great influence on the local flow field around that cavity. The stress at the boundary of the cavity is locally enhanced, and the collapse of the latter is induced. We have developed a numerical simulation that can satisfactorily explain our experimental findings. Furthermore we extend our numerical simulation so as to deal with three-dimensional cavities. These results can be applied to the prediction of landslides at the time of heavy rainfall and a new technique to predict anomalously fast convection of contaminants in underground water flow through cavity networks, as well as angiogenesis around tumor cells in the human liver.
2. We studied the generation of ripples and Barchan dunes due to viscous flow over the surface of the granular material. These results are applicable to the prediction of spread of desert area and the control of seabed level in the bay area.
3. Experiments on the collision of a vortex ring on the granular surface were made. We examined the dependence of the strength of the vortex ring on the engraved patterns left on the granular layer at the impingement.
4. Thin layer of granular materials were vertically vibrated, which revealed regular polygonal ripple patterns and undulations. We elucidated the mechanism of the formation of these patterns, and at the same time obtained the critical layer number that showed collective motion like those observed in continuum media. The behavior was partially explained by the buckling and bending motion of thin elastic layer. These studies are expected to bridge the gap between microscopic collision process and macroscopic fluid motion of the granular material, and our works are presented at major international conferences and domestic meetings.
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Research Products
(36 results)
