Temporal Mixing Behavior of Conservative Solute Transport through 2D Self-Affine Fractures
Temporal Mixing Behavior of Conservative Solute Transport through 2D Self-Affine Fractures
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DOI：
10.3390/pr6090158
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发表时间：
2018-09
期刊：
影响因子：
3.5
通讯作者：
Zhi Dou;B. Sleep;P. Mondal;Qiaona Guo;Jingou Wang;Zhifang Zhou
中科院分区：
文献类型：
--
作者：
Zhi Dou;B. Sleep;P. Mondal;Qiaona Guo;Jingou Wang;Zhifang Zhou
本文研究了Hurst指数和Peclet数（Pe）对自仿射裂缝中保守溶质的时间混合行为的影响。通过裂缝中的标量耗散率（SDR）量化混合。研究表明，可变孔径分布导致SDR的时间演化的局部波动，而SDR的时间演化的恒定孔径裂缝是平滑地减少作为时间的幂律函数。Peclet数在变孔径和常孔径裂缝混合的时间演化中起主导作用。在等孔径断裂中，当Peclet数相对较小时，Hurst指数对SDR随时间演化的影响可以忽略不计。当Peclet数相对较小时，在恒定孔径断裂中纵向SDR可以与全局SDR相关联。随着Peclet数的增加，纵向SDR高估了全球SDR。在变孔径裂缝中，由于纵向集中二阶矩的非单调增加，导致在物理上没有意义的SDR，从纵向SDR预测全局SDR是不合适的。
In this work, the influence of the Hurst exponent and Peclet number (Pe) on the temporal mixing behavior of a conservative solute in the self-affine fractures with variable-aperture fracture and constant-aperture distributions were investigated. The mixing was quantified by the scalar dissipation rate (SDR) in fractures. The investigation shows that the variable-aperture distribution leads to local fluctuation of the temporal evolution of the SDR, whereas the temporal evolution of the SDR in the constant-aperture fractures is smoothly decreasing as a power-law function of time. The Peclet number plays a dominant role in the temporal evolution of mixing in both variable-aperture and constant-aperture fractures. In the constant-aperture fracture, the influence of Hurst exponent on the temporal evolution of the SDR becomes negligible when the Peclet number is relatively small. The longitudinal SDR can be related to the global SDR in the constant-aperture fracture when the Peclet number is relatively small. As the Peclet number increases the longitudinal SDR overpredicts the global SDR. In the variable-aperture fractures, predicting the global SDR from the longitudinal SDR is inappropriate due to the non-monotonic increase of the longitudinal concentration second moment, which results in a physically meaningless SDR.