Direct characterization of solute transport in unsaturated porous media using fast X-ray synchrotron microtomography.
Direct characterization of solute transport in unsaturated porous media using fast X-ray synchrotron microtomography.
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DOI：
10.1073/pnas.2011716117
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发表时间：
2020-09-22
影响因子：
11.1
通讯作者：
Steeb H
中科院分区：
文献类型：
--
作者：
Hasan S;Niasar V;Karadimitriou NK;Godinho JRA;Vo NT;An S;Rabbani A;Steeb H
多孔材料中的溶质运移与许多工程和工业应用有关。这项研究提供了直接表征的时空行为的溶质运移在饱和和不饱和多孔介质中使用高分辨率四维同步辐射X射线成像。这项研究有两个关键影响：1）我们展示了一个直接表征任何多孔材料中溶质运移的工作流程，这使得更好地设计制造多孔材料和详细表征天然多孔材料，2）我们评估了现有理论中使用的基本假设，并确定了需要解决的主要理论差距，以更好地预测建模。溶质在非饱和多孔介质中的运移是一个复杂的过程，它具有一些不同于饱和条件下溶质运移的特征。这些特征的出现主要是由于不同的传输时间尺度在不同的区域的流动网络，可以分为流动和停滞的区域，主要是由平流和扩散，分别控制。在非饱和条件下，溶质穿透曲线显示出早到和很长的拖尾，这种类型的输运通常被称为非Fickian。这项研究直接通过非饱和多孔介质在三维空间的分辨率为3.25米和6秒的时间分辨率的传输特性。使用先进的高速，高空间分辨率，基于同步加速器的X射线计算机微断层扫描（sCT），我们获得了详细的信息，溶质通过玻璃珠填料在不同的饱和度。产生了大的实验数据集（>50 TB），同时在视场内的任何给定点处对溶质浓度随时间的演变进行成像。我们表明，流体的拓扑结构有一个关键的签名上的非Fickian运输，但需要包括在达西尺度溶质运移模型。三维（3D）的结果表明，在孔隙尺度上的充分混合的假设是无效的，即使在注入几个孔隙体积的浓度场在孔隙尺度上是不均匀的。此外，结果表明，色散随饱和度的变化，是两倍大的饱和度为0.52相比，在完全饱和的域。
Solute transport in porous materials is pertinent to many engineering and industrial applications. This research provides direct characterization of spatiotemporal behavior of solute transport in saturated and unsaturated porous media using high-resolution four-dimensional synchrotron X-ray imaging. This research has two key impacts: 1) we demonstrate a workflow for direct characterization of solute transport in any porous material, which allows better design of fabricated porous materials and detailed characterization of natural porous materials, and 2) we evaluate the underlying assumptions used in the existing theories and identify the major gaps in theories that need to be addressed for better predictive modeling. Solute transport in unsaturated porous materials is a complex process, which exhibits some distinct features differentiating it from transport under saturated conditions. These features emerge mostly due to the different transport time scales at different regions of the flow network, which can be classified into flowing and stagnant regions, predominantly controlled by advection and diffusion, respectively. Under unsaturated conditions, the solute breakthrough curves show early arrivals and very long tails, and this type of transport is usually referred to as non-Fickian. This study directly characterizes transport through an unsaturated porous medium in three spatial dimensions at the resolution of 3.25 m and the time resolution of 6 s. Using advanced high-speed, high-spatial resolution, synchrotron-based X-ray computed microtomography (sCT) we obtained detailed information on solute transport through a glass bead packing at different saturations. A large experimental dataset (>50 TB) was produced, while imaging the evolution of the solute concentration with time at any given point within the field of view. We show that the fluids’ topology has a critical signature on the non-Fickian transport, which yet needs to be included in the Darcy-scale solute transport models. The three-dimensional (3D) results show that the fully mixing assumption at the pore scale is not valid, and even after injection of several pore volumes the concentration field at the pore scale is not uniform. Additionally, results demonstrate that dispersivity is changing with saturation, being twofold larger at the saturation of 0.52 compared to that at the fully saturated domain.
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影响因子：
3.6
作者：
Dwarakanath, V;Kostarelos, K;Wade, WH
通讯作者：
Wade, WH
DOI：
10.1007/s00254-008-1464-0
发表时间：
2009-06-01
期刊：
ENVIRONMENTAL GEOLOGY
影响因子：
--
作者：
Joekar-Niasar, Vahid;Ataie-Ashtiani, Behzad
通讯作者：
Ataie-Ashtiani, Behzad
影响因子：
2.4
作者：
Bijeljic, Branko;Raeini, Ali;Blunt, Martin J.
通讯作者：
Blunt, Martin J.
影响因子：
5.4
作者：
Hasan, Sharul;Joekar-Niasar, Vahid;Sahimi, Muhammad
通讯作者：
Sahimi, Muhammad
影响因子：
2.5
作者：
Drakopoulos M;Connolley T;Reinhard C;Atwood R;Magdysyuk O;Vo N;Hart M;Connor L;Humphreys B;Howell G;Davies S;Hill T;Wilkin G;Pedersen U;Foster A;De Maio N;Basham M;Yuan F;Wanelik K
通讯作者：
Wanelik K