| Project/Area Number |
21580292
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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 |
Irrigation, drainage and rural engineering/Rural planning
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| Research Institution | Ibaraki University |
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Principal Investigator |
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| Project Period (FY) |
2009 – 2011
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| Project Status |
Completed (Fiscal Year 2011)
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| Budget Amount *help |
¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
Fiscal Year 2011: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2010: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2009: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
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| Keywords | 土壌物理 / コロイド工学 / 沈降特性 / 界面沈降速度 / 粘土フロック懸濁液 / 鉛直流路 / 流路径 / 流路数 / 壁面抵抗 / 管径 / 自己相似フロック / 透水理論 / ネットワーク構造 / カオリナイト / 凝集特性 / 試料濃度効果 / カオリナイトフロック / 自己相似構造 / 圧密沈降 |
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| Research Abstract |
The settling velocity of flocculated suspensions is determined as a function of effective floc volume fraction that is believed to be proportional to the solid volume fraction. However, flocs are very fragile and have an extended structure in suspensions so the effective volume changes easily. Therefore, a new method to determine effective volume from sediment volume was proposed and the effective volume was found to not be proportional to the solid volume. By using the measured effective volume, network formation was clarified to occur at an effective volume fraction over 0.25-0.30. Self-similar properties of floc structure were introduced for the analysis of settling velocity, and with the help of the relationship between settling velocity and effective volume fraction, fractal dimension was determined to be 2.35. On the other hand, at high volume fractions, many vertical channels were formed through the sediment and settling velocity tremendously increased. The flow rate in the channel was comparative to the computed maximum viscous-flow rate.
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