Effective diffusion coefficients in random packings of polydisperse hard spheres from two-point and three-point correlation functions
Effective diffusion coefficients in random packings of polydisperse hard spheres from two-point and three-point correlation functions
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DOI：
10.1063/1.4931153
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发表时间：
2015-09-28
影响因子：
3.2
通讯作者：
Torquato, S.
中科院分区：
文献类型：
--
作者：
Hlushkou, D.;Liasneuski, H.;Torquato, S.
我们用一个包含三点微结构参数σ（2）的解析公式计算了多分散硬球随机堆积中的有效扩散系数D-eff。固体体积分数在phi = 0.54和phi = 0.634之间的散装填料是使用实验确定的粒度分布，其特征在于不同的平均粒径和相关的标准偏差的计算机生成的。通过基于采样模板的方法，分别从两点和三点相关函数S-2和S-3计算参数sigma（2）。S-2和S-3的渐近分析结果与理论预测相吻合。近似解析公式计算的有效扩散系数接近使用随机行走粒子跟踪技术从模拟得到的。D-eff的值受填料的固体体积分数、球体的空间位置的影响，并且在较小程度上受颗粒的多分散性的影响。所提出的数值方法可以应用于仅从体现在phi和sigma中的几何信息来评估一般两相材料的有效扩散输运性质（2）。(C)2015 AIP Publishing LLC.
We evaluate the effective diffusion coefficient D-eff in random packings of polydisperse hard spheres with an analytical formula involving the three-point microstructural parameter sigma(2). Bulk packings with solid volume fraction between phi = 0.54 and phi = 0.634 were computer-generated using experimentally determined particle size distributions characterized by different mean particle diameter and associated standard deviation. The parameter sigma(2) was calculated from two-and three-point correlation functions S-2 and S-3, respectively, via an approach based on sampling templates. Results of the asymptotic analysis for S-2 and S-3 compare favorably with theoretical predictions. Effective diffusivities calculated by the approximate analytical formula are close to those obtained from simulations using a random-walk particle-tracking technique. The values of D-eff are affected by the packings' solid volume fraction, the spatial positions of the spheres, and to a far lesser extent by the particles' polydispersity. The proposed numerical approach can be applied to evaluate effective diffusive transport properties of general two-phase materials just from the geometrical information embodied in phi and sigma(2). (C) 2015 AIP Publishing LLC.