Laboratory experiments on dispersive transport across interfaces: The role of flow direction
Laboratory experiments on dispersive transport across interfaces: The role of flow direction
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DOI：
10.1029/2008wr007342
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发表时间：
2008-12
影响因子：
5.4
通讯作者：
B. Berkowitz;A. Cortis;I. Dror;H. Scher
中科院分区：
文献类型：
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作者：
B. Berkowitz;A. Cortis;I. Dror;H. Scher
我们提出了保守示踪剂在不同多孔材料界面上的不对称色散输运的实验证据。测量了示踪脉冲在稳态流场中通过包含相邻粗孔和细孔介质段的柱时的突破曲线。示踪剂从细介质到粗介质的迁移速度明显快于从粗介质到细介质的迁移速度。随着流量的增加，突破曲线之间的差异逐渐减小。我们认为，这种行为表明，在非均质界面的常驻浓度分布中，存在显著的、随时间变化的示踪剂积累。使用平流-色散方程的传统建模被证明无法捕获这种不对称行为。然而，在粒子跟踪模拟中观察到界面处的示踪剂积累，这可能与观察到的突破曲线的不对称性有关。
We present experimental evidence of asymmetrical dispersive transport of a conservative tracer across interfaces between different porous materials. Breakthrough curves are measured for tracer pulses that migrate in a steady state flow field through a column that contains adjacent segments of coarse and fine porous media. The breakthrough curves show significant differences in behavior, with tracers migrating from fine medium to coarse medium arriving significantly faster than those from coarse medium to fine medium. As the flow rate increases, the differences between the breakthrough curves diminish. We argue that this behavior indicates the occurrence of significant, time‐dependent tracer accumulation in the resident concentration profile across the heterogeneity interface. Conventional modeling using the advection‐dispersion equation is demonstrated to be unable to capture this asymmetric behavior. However, tracer accumulation at the interface has been observed in particle‐tracking simulations, which may be related to the asymmetry in the observed breakthrough curves.