Anomalous Solute Transport in Cemented Porous Media: Pore‐scale Simulations

Hou, Yusong; Jiang, Jian-Guo; Wu, Jichun

doi:10.2136/sssaj2017.04.0125

Cited by 6 publications

(7 citation statements)

References 40 publications

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“…It has been observed that in many cases, two-dimensional simulation schemes can grasp the majority of the physical processes of solute transport and reduce the simulation complexity and calculation costs, compared with threedimensional simulations. In addition, in the previous study, we found that when the cementation degree increases, the velocity probability distribution of fluid in 2D media and 3D media and its change trend are similar [28,29]. Therefore, this study performed two-dimensional simulations at the pore scale for the purpose of exploring the solute dilution processes in porous media with different cementation degrees.…”

Section: Methodsmentioning

confidence: 89%

Using a Pore-Scale Modelling Approach to Study Solute Dilution Process through Cemented Porous Media

Hou

Liu

et al. 2022

Geofluids

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In this study, a pore-scale simulation method is applied to quantitatively study the variation of solute dilution through porous media with different cementation degrees and explore the corresponding mechanisms. The study results indicated that the cementation degrees of the solid grains had a significant effect on the solute dilution process and that the influence was very complicated. The complexity was manifested in that the effect of rising cementation degree on the solute dilution process would be different or even completely opposite in the porous media in which the solid grains cement slightly with that in porous media with a higher cementation degree. For example, for the porous media in which the solid grains were slightly cemented (the percentage of the cemented solid grains P c is less than 40%), the dilution effects became enhanced with the increase of cementation degree. Then, after P c increased to about 55%, the dilution effect was obviously weakened, and the solute was in an incomplete dilution state for a long period of time. In addition, this study found that the properties of the flow fields may vary greatly in porous media with different cementation degrees and that those differences in the flow fields resulted in the distinct behavior of the solute dilution. It is interesting to note that a more heterogeneous flow field had not necessarily led to the enhancement of the dilution process.

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Section: Methodsmentioning

confidence: 89%

Using a Pore-Scale Modelling Approach to Study Solute Dilution Process through Cemented Porous Media

Hou

Liu

et al. 2022

Geofluids

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“…In many laboratory and field scale studies [12][13][14][15], results show that the solute transport followed the non-Fickian transport. By fitting the experimentally measured or directly simulated breakthrough curves of solute plumes with continuous-time random walk (CTRW) models, some studies [16][17][18] indicated a strong link between the non-Fickian transport and heterogeneity of porous media. The varied geometry of pore channels and the cementation of solid grains are very common in natural solids, resulting in the heterogeneity of porous media.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies indicated that the characteristics of pore channels such as connectivity or pore particle distribution could affect the flow field and solute transport processes [19,20]. The evolution of solute mixing in porous media with different degrees of heterogeneity is caused by the changes in pore channel geometry and solid grains due to the cementation of porous media [17]. However, little attention has been focused on this problem until now.…”

Section: Introductionmentioning

confidence: 99%

Effects of Cemented Porous Media on Temporal Mixing Behavior of Conservative Solute Transport

Dou

Zhang

Zhou

et al. 2019

Water

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The cementation of porous media leads to the variation of the pore space and heterogeneity of the porous media. In this study, four porous media (PM1, PM2, PM3, and PM4) with the different radii of solid grains were generated to represent the different cementation degrees of the porous media. The direct simulations of flow and conservative solute transport in PM1-4 were conducted to investigate the influence of the cemented porous media and Peclet number (Pe) on the temporal mixing behavior. Two metrics, scalar dissipation rates (SDR) and dilution index, were employed to quantify the temporal mixing behavior. It was found that the spatial velocity variability of the flow field was enhanced as cementation degree increased. The results of the coefficient of velocity variation (CV U ) increased from 0.943 to 2.319 for PM1-4. A network consisted of several preferential flow paths was observed in PM1-4. The preferential flow enhanced the mixing of the conservative solute but had a negative influence on the mixing of the solute plume when the cemented solid grains formed several groups, and there were some stagnant regions where the flow was almost immobile. As the Pe increased, for PM1-3, the exponent of the best-fitting power law of the global SDR decreased. At the case of Pe = 400, the slope of the global SDR reduced to around −1.9. In PM4 where the preferential flow was enhanced by the cemented solid grains, the slope of the global SDR increased as the Pe increased. The global SDR results indicated that the temporal mixing behavior followed a Fickian scaling (SDR ∝ pv −1.5 ) in the early stage (Pv < 0.05), while the mixing behavior turned to be non-Fickian in the late stage. The transition time from the Fickian scaling to the non-Fickian scaling was found to be sensitive to the cementation degree of the porous media.

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“…However, increasing numerical and experimental evidences have demonstrated that a realistic solute transport process exhibits behavior that deviates systematically from the predictions of the ADE (Hou et al, 2018; Scheven et al, 2005; Wirner et al, 2014). For example, by fitting measured breakthrough curves (BTCs) with the ADE, Levy and Berkowitz (2003) have shown that the measured BTCs are distinctly different from the sigmoid BTCs predicted by the ADE.…”

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confidence: 99%

“…There are many studies that have demonstrated that the CTRW model can provide a convincing description of the time behavior of the transport process over a wide range of cases (Berkowitz et al, 2000; Bijeljic et al, 2013; Xiong et al, 2006). Unfortunately, little validation has been conducted for the application of CTRW to describe the time behavior of solute migration in cemented porous media (Hou et al, 2018). In this study, the cementation degree is measured quantitatively by the ratio of the cemented solid volume (the volume occupied by multiple solid grains) to the total solid volume.…”

mentioning

confidence: 99%

Time Behavior of Anomalous Solute Transport in Three‐Dimensional Cemented Porous Media

Hou

Jiang

2019

Soil Science Soc of Amer J

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We quantitatively explore and explain the different time behavior of anomalous solute transport in three‐dimensional (3D) porous media with different cementation degrees. We find that the temporal evolution of the breakthrough curves (BTCs), spatial moments and propagators representing the time behavior of the transport varies significantly in each case with rising cementation degree. For example, the early breakthrough and long tail in the BTCs are enhanced simultaneously when the cementation degree increases, implying that the solute transport is anomalous. Correspondingly, instead of both the first and second central moments growing linearly with time as described by the traditional advection‐dispersion equation (ADE), the relationship between the second central moment M2 and time gradually transitions from an approximate linear relationship into a nonlinear relationship. This indicates that the scale effect is enhanced in the porous media with larger cementation degree. In addition, the propagator is characterized by a more remarkable and more persistent stagnant concentration peak when the cementation degree rises. Our simulations also demonstrate that the CTRW model can capture the simulated BTCs and quantitatively predict the temporal evolution of the first two moments of the solute plume. Finally, we explain the mechanism of the different time behavior of solute transport via the characteristics of the flow field. Core Ideas Time behavior of solute transport varies radically with rising cementation degree. CTRW model can characterize the different time behavior of solute transport. The changing characteristics of flow field cause the different time behavior.

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Anomalous Solute Transport in Cemented Porous Media: Pore‐scale Simulations

Cited by 6 publications

References 40 publications

Using a Pore-Scale Modelling Approach to Study Solute Dilution Process through Cemented Porous Media

Using a Pore-Scale Modelling Approach to Study Solute Dilution Process through Cemented Porous Media

Effects of Cemented Porous Media on Temporal Mixing Behavior of Conservative Solute Transport

Time Behavior of Anomalous Solute Transport in Three‐Dimensional Cemented Porous Media

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