Understanding how porosity gradients can make a better filter using homogenization theory
Understanding how porosity gradients can make a better filter using homogenization theory
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DOI：
10.1098/rspa.2015.0464
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发表时间：
2015-10-08
影响因子：
3.5
通讯作者：
Bruna, M.
中科院分区：
文献类型：
--
作者：
Dalwadi, M. P.;Griffiths, I. M.;Bruna, M.
孔隙度随深度减小的过滤器通常比孔隙度均匀的过滤器更能有效地从流体中去除溶质。我们通过均质化理论的扩展来研究这一现象，该理论解释了微观结构的宏观变化。在本文的第一阶段，我们均匀化了具有近周期微观结构的过滤器的流动问题和由于平流、扩散和过滤器吸附引起的溶质输送问题。在第二阶段，我们使用计算效率高的均匀化方程来研究和量化为什么孔隙度梯度可以提高过滤效率。我们发现孔隙度梯度对吸附均匀性的影响远大于对总吸附量的影响。这使我们能够理解降低孔隙度如何通过降低局部堵塞的风险来提高过滤效率，同时保持污染物的总去除速度。
Filters whose porosity decreases with depth are often more efficient at removing solute from a fluid than filters with a uniform porosity. We investigate this phenomenon via an extension of homogenization theory that accounts for a macroscale variation in microstructure. In the first stage of the paper, we homogenize the problems of flow through a filter with a near-periodic microstructure and of solute transport owing to advection, diffusion and filter adsorption. In the second stage, we use the computationally efficient homogenized equations to investigate and quantify why porosity gradients can improve filter efficiency. We find that a porosity gradient has a much larger effect on the uniformity of adsorption than it does on the total adsorption. This allows us to understand how a decreasing porosity can lead to a greater filter efficiency, by lowering the risk of localized blocking while maintaining the rate of total contaminant removal.