Predictions of non-Fickian solute transport in different classes of porous media using direct simulation on pore-scale images
Predictions of non-Fickian solute transport in different classes of porous media using direct simulation on pore-scale images
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DOI：
10.1103/physreve.87.013011
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发表时间：
2013-01-10
影响因子：
2.4
通讯作者：
Blunt, Martin J.
中科院分区：
文献类型：
--
作者：
Bijeljic, Branko;Raeini, Ali;Blunt, Martin J.
我们提出了通过多孔介质的Micro-CT图像传输的预测，其中包括对相关结构、速度和羽流演化的动力学的分析。我们通过微珠、砂岩和碳酸盐的毫米大小的三维图像来模拟溶质的传输，这些图像代表了具有越来越大的孔隙尺度复杂性的多孔介质。流场计算采用N-S方程求解，颗粒平流运动采用流线模拟方法，扩散采用随机游动方法。我们展示了计算的珠粒、砂岩和碳酸盐的传播子(浓度作为位移的函数)如何依赖于速度分布的宽度。砂岩中较窄的速度分布导致最小的异常行为，传播子迅速变成高斯形状；较宽的速度分布在砂岩中产生一个小的不动浓度峰，大的二次移动峰以接近平均流速移动；在速度分布最宽的碳酸盐岩中，停滞浓度峰持续存在，较小的二次移动峰出现得较慢，具有高度异常行为的特征。这定义了三种介质中不同类型的传输，并量化了孔结构对传输的影响。由该模型得到的传播子与Schven，Verganelakis，Harris，Johns和Gladden，Phys在类似核磁共振实验中测得的结果符合得很好。《流体》17,117107(2005年)。DOI：10.1103/PhysRevE.87.013011
We present predictions of transport through micro-CT images of porous media that include the analysis of correlation structure, velocity, and the dynamics of the evolving plume. We simulate solute transport through millimeter-sized three-dimensional images of a beadpack, a sandstone, and a carbonate, representing porous media with an increasing degree of pore-scale complexity. The Navier-Stokes equations are solved to compute the flow field and a streamline simulation approach is used to move particles by advection, while the random walk method is employed to represent diffusion. We show how the computed propagators (concentration as a function of displacement) for the beadpack, sandstone, and carbonate depend on the width of the velocity distribution. A narrow velocity distribution in the beadpack leads to the least anomalous behavior, where the propagators rapidly become Gaussian in shape; the wider velocity distribution in the sandstone gives rise to a small immobile concentration peak, and a large secondary mobile peak moving at approximately the average flow speed; in the carbonate with the widest velocity distribution, the stagnant concentration peak is persistent, with a slower emergence of a smaller secondary mobile peak, characteristic of highly anomalous behavior. This defines different types of transport in the three media and quantifies the effect of pore structure on transport. The propagators obtained by the model are in excellent agreement with those measured on similar cores in nuclear magnetic resonance experiments by Scheven, Verganelakis, Harris, Johns, and Gladden, Phys. Fluids 17, 117107 (2005). DOI: 10.1103/PhysRevE.87.013011