| Project/Area Number |
08680549
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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 |
Environmental dynamic analysis
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| Research Institution | GRADUATE SCHOOL OF HUMANITIES AND SCIENCES OCHANOMIZU UNIVERSITY |
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Principal Investigator |
KAWAMURA Tetsuya お茶の水女子大学, 人間文化研究科, 教授 (40143383)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Tsutomu 鳥取大学, 工学部, 教授 (00093063)
SATO Hiroshi お茶の水女子大学, 人間文化研究科, 教授 (10017197)
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| Project Period (FY) |
1996 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1998: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1997: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1996: ¥800,000 (Direct Cost: ¥800,000)
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| Keywords | movement of sand dune / effect of vegetation / numerical simulation / flow around circular cylinder / barchan dune / sand transfer by wind / Tottori and dune / velocity of movement / 表面摩擦 / 移動速度と高さの関係 / 環境問題 / 砂丘移動現象 / コンピュータグラフィクス / 乾燥地 / 数値流体力学 / 実験流体力学 |
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| Research Abstract |
The flow above a sand dune is computed numerically and the movement of the sand is investigated, The effect of the vegetation on the movement of the sand is also studied. The numerical method employed in this study can be divided into three parts : (a) calculation of the air flow above the sand dune ; (b) estimation of the sand transfer caused by the flow through the friction ; (c) determination of the shape of the ground. Since the computational area is changed due to step (c), this procedure has to be repeated for the next time step.
At first, two dimensional flow field over the sand dune of the triangular cross section and the movement of the dune is computed. The effect of the height of the dune and that of the vegetation on the movement are also investigated for this sand dune. The laminar flow calculations as well as the turbulence calculations by the simple mixing length model are performed. Next, we extend this method to three dimensional calculation. We simulate the formation of the barchan sand dune of crescent shape which is usually observed in the actual desert. The simulated dune, which has initially elliptic cross section, develops wings from the each end of the dune and a steep slope between them.
The flow around a circular cylinder standing on the sand is computed numerically and the movement of the sand is estimated. From this simulation, it is found that the horseshoe vortex scoops out the ground in front of the cylinder and that the wake makes the sand accumulate in the rear region. The dented region becomes deeper as the cylinder leans to the windward. Moreover, three dimensional flow field over the complex surface of the Tottori sand dune are computed in order to apply the numerical method to practical problems.
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