Abstract One of the primary particle-retention mechanisms in a filtration process is straining, which happens when the size of a particle is larger than the pore throat trapping it. The occurrence of straining depends on both the particle size distribution (PSD) of the suspension and the pore throat size distribution (PoSD) of the filter, with measurement of the latter being especially difficult. This paper presents a new approach for evaluating the PoSD of a filter medium using a discrete element method (DEM). The approach computes the filter efficiency (FE), defined as the fraction of particles of a certain size retained by the filter, for incremental particle sizes in a filtration process. Special care was taken to turn off the interactions between injected particles in the simulation so that the computed filter efficiencies reflect an incremental sampling of pore throat sizes, and thereby can be used to infer the PoSD. Good agreement was observed between the simulated and theoretical PoSDs in an ideal sieve and a simple cubic packing case. The study showed that for a monodisperse random close packing (RCP) of spherical grains, the largest pore throat is about 1/4.5 of the grain size, and the smallest pore throat is about 1/6.6 of the grain size. For a polydisperse RCP formed by 20–40 mesh grains, the largest pore throat is about 1/5.3 of the effective grain size, and the smallest pore throat is about 1/10 of the effective grain size. The approach can be easily extended to evaluate the PoSD of any type of filter medium, including RCPs with any PSD. The PoSD computed provides essential information for filter layer design and selection.

中文翻译：

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基于 DEM 的过滤介质孔喉尺寸分布评估方法

摘要 过滤过程中主要的颗粒滞留机制之一是过滤，当颗粒的尺寸大于捕获它的孔喉时就会发生过滤。应变的发生取决于悬浮液的粒径分布 (PSD) 和过滤器的孔喉尺寸分布 (PoSD)，后者的测量尤其困难。本文提出了一种使用离散元法 (DEM) 评估过滤介质 PoSD 的新方法。该方法计算过滤效率 (FE)，定义为过滤器保留的特定尺寸颗粒的分数，用于过滤过程中的增量颗粒尺寸。特别注意关闭模拟中注入颗粒之间的相互作用，以便计算出的过滤效率反映孔喉尺寸的增量采样，从而可用于推断 PoSD。在理想筛子和简单立方填料情况下的模拟和理论 PoSD 之间观察到良好的一致性。研究表明，对于球形颗粒的单分散随机密堆积（RCP），最大孔喉约为颗粒尺寸的 1/4.5，最小孔喉约为颗粒尺寸的 1/6.6。对于由 20～40 目颗粒形成的多分散 RCP，最大孔喉约为有效粒径的 1/5.3，最小孔喉约为有效粒径的 1/10。该方法可以很容易地扩展到评估任何类型过滤介质的 PoSD，包括具有任何 PSD 的 RCP。计算的 PoSD 为过滤层设计和选择提供了基本信息。