Measurement and analysis of non-Fickian dispersion in heterogeneous porous media
Measurement and analysis of non-Fickian dispersion in heterogeneous porous media
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DOI：
10.1016/s0169-7722(02)00204-8
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发表时间：
2003-07-01
影响因子：
3.6
通讯作者：
Berkowitz, B
中科院分区：
文献类型：
--
作者：
Levy, M;Berkowitz, B
在实验室实验中测量了污染物在各种非均匀多孔介质中的穿透行为，并根据经典的平流-弥散方程(ADE)和连续时间随机游走(CTRW)框架对其进行了评估。非均质性可能导致非费克输运模式，这种模式在突破曲线上以“异常”的早到和晚到为特征。实验是在两个中等规模的实验室流动池中进行的，其中填充了指定粒度的清洁筛砂。进行了三组实验，分别使用“均匀”填料、使用两种粒度的沙子的随机非均匀填料和使用三种粒度的沙子的指数相关结构。在流入储水池监测氯化钠示踪剂浓度，在流出储水池测量氯化钠示踪剂浓度。然后，通过与ADE和CTRW配方的拟合解进行比较，分析穿透曲线。在包括“均匀”系统在内的所有三个系统中，都观察到了费克输运和非费克输运之间的细微但可测量的差异。定量分析表明，CTRW理论比ADE更有效地刻画了穿透曲线的完整形状。(C)2003 Elsevier Science B.V.保留所有权利。
Contaminant breakthrough behavior in a variety of heterogeneous porous media was measured in laboratory experiments, and evaluated in terms of both the classical advection-dispersion equation (ADE) and the continuous time random walk (CTRW) framework. Heterogeneity can give rise to non-Fickian transport patterns, which are distinguished by "anomalous" early arrival and late time tails in breakthrough curves. Experiments were conducted in two mid-scale laboratory flow cells packed with clean, sieved sand of specified grain sizes. Three sets of experiments were performed, using a "homogeneous" packing, a randomly heterogeneous packing using sand of two grain sizes, and an exponentially correlated structure using sand of three grain sizes. Concentrations of sodium chloride tracer were monitored at the inflow reservoir and measured at the outflow reservoir. Breakthrough curves were then analyzed by comparison to fitted solutions from the ADE and CTRW formulations. In all three systems, including the "homogeneous" one, subtle yet measurable differences between Fickian and non-Fickian transport were observed. Quantitative analysis demonstrated that the CTRW theory characterized the full shape of the breakthrough curves far more effectively than the ADE. (C) 2003 Elsevier Science B.V. All rights reserved.