Non-uniform water and solute flow in uniform soil media

均匀土壤介质中的水和溶质流动不均匀

• 批准号: 13460102
• 负责人: SHIOZAWA Sho
• 金额: $ 3.9万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13460102/
• 关键词: finger flow; Wetting front; Darcy's equation; Soli water flow; infiltration; 溶質分散係数; 移流分散方程式; 不飽和流; 不均一性; 電気伝導度; 濃度置換

Distinct water-content profiles, having saturated θ-bumps at and immediately behind the wetting front, were observed in narrow columns (9 mm I.D.) of homogeneous air-dry glass beads under downward 1D-infiltration. with applied water fluxes at lower than the saturated hydraulic conductivity. The infiltrating water content profiles and the position of the wetting front as a function of time were also calculated based on Richards' equation using an independently-measured hydraulic conductivity function, K(θ), and water retention characteristic, θ(h), of the drainage process, and by applying a pressure boundary condition, h_<we>, which is almost atmospheric pressure, at the moving wetting front. The good agreement between the calculated profiles and the observed confirms that the dynamic water entry pressure (where θ(h_<we>) is the saturated water content), does exist for air-dried glass beads, although it is in contradiction with the modern theory of unsaturated water flow in porous media. This physical property of the dry media creates an upward negative pressure profile behind the wetting front that would inevitably produce finger flow if the column diameter were larger. At the wetting front, the water content and pressure should be completely discontinuous at the level of pore size, and hence Darcy's equation cannot be applied across the interface between the air-dry and saturated media.

在均质风干玻璃珠的窄柱（直径9 mm）中，在向下1d渗透下，观察到明显的含水量分布，在湿润锋处及其后面有饱和θ-凸起。施加的水通量低于饱和水导率。利用独立测量的导水率函数K（θ）和排水过程的保水特性θ(h)，并在移动的湿润锋处应用压力边界条件h_< w>，近似于大气压，基于Richards方程计算了浸润含水率剖面和湿润锋位置随时间的变化。计算剖面与实测值吻合较好，证实了风干玻璃微珠的动态入水压力（其中θ（h_<我们>）为饱和含水量）是存在的，尽管这与现代多孔介质中非饱和水流理论存在矛盾。干燥介质的这一物理特性在湿润锋后产生了向上的负压分布，如果柱直径较大，将不可避免地产生指流。在润湿前沿，含水量和压力在孔径水平上应该是完全不连续的，因此达西方程不能在风干介质和饱和介质的界面上应用。

项目成果

Sho Shiozawa, Haruyuki Fujimaki: "Unexpected water content profiles under flux-limited one-dimensional downward infiltration into initially dry glass beads"Water Resources.Research. (印刷中). (2004)

Sho Shiozawa、Haruyuki Fujimaki：“通量限制的一维向下渗透到最初干燥的玻璃珠中的意外含水量”水资源研究（2004 年出版）。

Sho Shiozawa, Haruyuki Fujimaki: "Unexpected wafer content profiles under flux-limited one-dimensional downward infiltration into initially dry glass beads"Water Resources. Research. (in print). (2004)

Sho Shiozawa、Haruyuki Fujimaki：“在流量限制的一维向下渗透到最初干燥的玻璃珠中时出现意外的晶圆含量分布”水资源。

塩沢 昌, 家田浩之: "土壌中の吸着、排除をともなうイオンの移動速度"土壌物理学会シンポジウム講演要旨集. 58-59 (2002)

Masaru Shiozawa、Hiroyuki Ieda：“与土壤中吸附和排斥相关的离子的运动速度”土壤物理学会研讨会论文集 58-59（2002 年）。

Sho Shiozawa, Haruyuki Fujimaki: "Unexpected water content profiles under flux-limited one-dimensional downward infiltration into initially dry glass beads"Water Resources. Research. (印刷中). (2004)

Sho Shiozawa，Haruyuki Fujimaki：“流量限制的一维向下渗透到最初干燥的玻璃珠中的意外含水量”水资源研究（2004 年）。