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Dispersivity variations of solute transport in heterogeneous sediments: numerical and experimental study
Stochastic Environmental Research and Risk Assessment ( IF 3.9 ) Pub Date : 2021-06-05 , DOI: 10.1007/s00477-021-02040-x
Ziqi Ma , Zhenxue Dai , Xiaoying Zhang , Chuanjun Zhan , Huili Gong , Lin Zhu , Corey D. Wallace , Mohamad Reza Soltanian

Heterogeneity significantly effects the accuracy of flow and contaminant transport prediction in subsurface formations. The spatial correlation structure of hydraulic conductivity (K) is a crucial factor to characterize the heterogeneous architecture. In presented study, the relationship between the spatial correlation structure of K and plume dispersion is analyzed through the integration of experimental and numerical simulation approaches. A detailed description on the sedimentary facies types in a column experiment is obtained to ensure the accuracy of the heterogeneous characterization. The spatial correlation structure of K is analyzed with the components of ln(K) covariance and facies transition probability structures. Lagrangian-based models are developed to estimate solute dispersion in nonreactive tracer injection experiments. The results show that the model can predict plume spreading accurately when the spatial correlation structure is well defined. The dispersivities calculated by the Lagrangian-based model are slightly higher than those obtained from the solute transport experiments. Further, the upscaled dispersivity derived from the transition probability is dominated by the cross-transition probability structure, while the contribution of the auto-transition terms is quite small. The numerical modeling results confirm that the upscaled dispersivity can reproduce the solute breakthrough in the heterogeneous sediment well. The scale dependence of dispersion is strengthened when the flow direction is perpendicular to the bedding plane where the conductivity dramatically changes along the flow path in a layered bedding sediment.



中文翻译:

非均质沉积物中溶质运移的分散性变化:数值和实验研究

异质性显着影响地下地层中流动和污染物传输预测的准确性。水力传导率 ( K )的空间相关结构是表征异质结构的关键因素。在目前的研究中,通过实验和数值模拟方法的结合,分析了K的空间相关结构与羽流扩散之间的关系。通过柱实验对沉积相类型进行了详细描述,以确保非均质表征的准确性。用ln( K)的分量分析K的空间相关结构协方差和相转移概率结构。开发了基于拉格朗日的模型来估计非反应示踪剂注入实验中的溶质扩散。结果表明,当空间相关结构明确定义时,该模型可以准确地预测羽流扩散。由基于拉格朗日的模型计算的弥散率略高于从溶质输运实验获得的弥散率。此外,从转移概率推导出的放大的分散性由交叉转移概率结构主导,而自动转移项的贡献非常小。数值模拟结果证实,放大的弥散度可以很好地再现非均质沉积物中的溶质突破。

更新日期:2021-06-05
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