Geometrical interpretation of long-time tails of first-passage time distributions in porous media with stagnant parts.
Geometrical interpretation of long-time tails of first-passage time distributions in porous media with stagnant parts.
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DOI：
10.1103/physreve.90.013025
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发表时间：
2014-07
期刊：
影响因子：
--
通讯作者：
Frank Wirner;Christian Scholz;C. Bechinger
中科院分区：
文献类型：
--
作者：
Frank Wirner;Christian Scholz;C. Bechinger
使用实验与数值相结合的方法，我们研究了二维多孔材料中小颗粒的首次通过时间分布（FPTD）。低孔隙率结构中的分布显示出持续的长时间尾部，其与佩克莱特数无关，因此不能用平流扩散方程来解释。相反，我们的结果表明这些尾巴是由停滞区域（即粒子被捕获一段时间的静止区域）引起的。将测量的 FPTD 与颗粒停留时间的解析表达式进行比较，该颗粒在有限区域中扩散并能够通过小孔逸出，与我们的数据具有良好的一致性。
Using a combined experimental-numerical approach, we study the first-passage time distributions (FPTD) of small particles in two-dimensional porous materials. The distributions in low-porosity structures show persistent long-time tails, which are independent of the Péclet number and therefore cannot be explained by the advection-diffusion equation. Instead, our results suggest that these tails are caused by stagnant, i.e., quiescent areas where particles are trapped for some time. Comparison of measured FPTD with an analytical expression for the residence time of particles, which diffuse in confined regions and are able to escape through a small pore, yields good agreement with our data.