Revisit of advection-dispersion equation model with velocity-dependent dispersion in capturing tracer dynamics in single empty fractures
Revisit of advection-dispersion equation model with velocity-dependent dispersion in capturing tracer dynamics in single empty fractures
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重新审视具有速度相关色散的平流色散方程模型，用于捕获单空裂缝中的示踪剂动力学
DOI：
10.1007/s42241-018-0134-2
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发表时间：
2018-11
影响因子：
2.5
通讯作者：
Qian Jiazhong
中科院分区：
文献类型：
--
作者：
Wang Mu;Zhao Weidong;Garrard R;Zhang Y;Liu Y;Qian Jiazhong
污染物在裂隙介质中运移的定量分析是解决水质相关科学和工程问题的关键，而弥散系数是溶质运移模型中一个重要而又难以确定的参数。以往的研究表明，标准对流弥散方程（ADE）模式中的弥散系数（D）可以近似为D =αvλ（其中α为弥散度）。首先，在不同水力梯度条件下，进行了一系列示踪剂在单空裂缝中的运移实验。其次，基于ADE模型模拟确定示踪剂穿透曲线，得到不同裂缝粗糙度和流速下的弥散系数。分析了不同流动条件下λ的变化趋势。结果表明，虽然标准的ADE模型不能用于表征示踪剂BTC的后期拖尾，可能是由于溶质保留，这个简单的模型可以模拟大多数溶质质量动力学移动通过裂缝，因此可以提供信息，用于估计在适合于非菲克运输的简约模型中的分散。得出以下三个结论：（1）根据ADE模拟，突破曲线的峰值随着粗糙度的增加而提前;（2）λ值一般随着裂缝相对粗糙度的增加而减小;（3）当光滑裂缝中分散以分子扩散为主时，λ值约等于2.0。
An accurate quantification of the contaminant transport through fractured media is critical for dealing with water-quality related scientific and engineering issues, where the dispersion coefficient is an important and elusive parameter for the solute transport modeling. Many previous studies show that the dispersion coefficient (D) in the standard advection-dispersion equation (ADE) model can be approximated byD=αvλ(whereαis the dispersivity), a formula to be revisited systematically in this study by laboratory experiments and model analysis. First, a series of tracer transport experiments in single empty fractures are conducted in cases of different hydraulic gradients. Second, the tracer breakthrough curves are determined by simulations based on the ADE model, to obtain the dispersion coefficients corresponding to various fracture roughnesses and flow velocities. A varying trend ofλis analyzed under different flow conditions. Results show that although the standard ADE model cannot be used to characterize the late-time tailing of the tracer BTCs, likely due to the solute retention, this simple model can simulate most of the solute mass dynamics moving through fractures and may therefore provide information for estimating the dispersion in parsimonious models appropriate for the non-Fickian transport. The following three conclusions are drawn: (1) the peak of the breakthrough curves comes earlier with increasing the roughness, according to the ADE simulation, (2) the value ofλgenerally decreases as the relative roughness of the fracture increases, (3) the value ofλis approximately equal to 2.0 when the dispersion is dominated by the molecular diffusion in the smooth fracture.
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影响因子：
4.7
作者：
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通讯作者：
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影响因子：
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影响因子：
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作者：
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通讯作者：
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