Multifaceted analysis of non-linearity of density-driven flow in shallow groundwater
| Project/Area Number |
16K07971
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Agricultural environmental engineering/Agricultural information engineering
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2017: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2016: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
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| Keywords | 地下水 / 密度流 / 非線形性 / 間隙ネットワーク / パーコレーション理論 / Waylandテスト / アトラクタ再構成 / Hele-Shaw流 / フィンガリング / 格子ボルツマン法 / フィンガリング現象 / 非混合性流体 / 分岐 / レイリー数 / 自励振動 / モデル化 |
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| Outline of Final Research Achievements |
When high-density-fluid enters shallow groundwater, its flow regime will change depending on velocity of the groundwater and/or the density of inflow fluid. This phenomena is referred to as bifurcation, and this derives from non-linearity of the governing equations. The bifurcation, which had been confirmed through computational experiments, was also ascertained by visualization experiments of seepage flow. But irregular fluctuation was seen in the laboratory experiments, while only simple harmonic wave had been seen in the computational experiments. So, non-linear time series analysis, such as the attractor reconstruction and Wayland test, was done. Those provided evidences that the irregular fluctuation is chaotic one.
In the modeling study of seepage flow through porous media using a pore-network model, it was shown that sub-networks which are composed by invadable pores play a critical role in imbibition and drainage processes from the perspective of the percolation theory.
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| Academic Significance and Societal Importance of the Research Achievements |
地下水における密度流は，火山性熱源に由来する数百年といった時間的・空間的スケールの大きな対流現象が知られているが，浅層地下水においても，条件がそろえば数週間から数か月といったオーダーの対流現象が起こることが示された．対流を伴う高密度の流体の侵入は，下流に広く拡散しながら広がるためこの現象の解明は社会的にも意義がある．
また，多孔質媒体の間隙内への流体の侵入にも，フィンガー流や一様侵入といった侵入様式が存在するが，その発生メカニズムが示されたことは学術的に意義が高い．これにより，空気侵入圧，水侵入圧といった用語がさす状態を明確に規定することができるようになった．
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Report
(4 results)
Research Products
(16 results)
