Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
Soft Matter. 2017 Dec 6;13(47):9015-9023. doi: 10.1039/c7sm01588g.
The diffusiophoretic motion of suspended colloidal particles under one-dimensional solute gradients is solved using numerical and analytical techniques. Similarity solutions are developed for the injection and withdrawal dynamics of particles into semi-infinite pores. Furthermore, a method of characteristics formulation of the diffusion-free particle transport model is presented and integrated to realize particle trajectories. Analytical solutions are presented for the limit of small particle diffusiophoretic mobility Γ relative to the solute diffusivity D for particle motions in both semi-infinite and finite domains. Results confirm the build up of local maxima and minima in the propagating particle front dynamics. The method of characteristics is shown to successfully predict particle motions and the position of the particle front, although it fails to accurately predict suspended particle concentrations in the vicinity of sharp gradients, such as at the particle front peak seen in some injection cases, where particle diffusion inevitably plays an important role. Results inform the design of applications in which the use of applied solute gradients can greatly enhance particle injection into and withdrawal from pores.
运用数值和分析技术研究了悬浮胶体颗粒在一维溶质梯度下的扩散运动。为颗粒进入半无限孔隙的注入和抽取动力学开发了相似解。此外，提出了一种无扩散颗粒输运模型的特征线解法，并对其进行了积分以实现颗粒轨迹。对于颗粒在半无限和有限区域中的扩散迁移率 Γ相对于溶质扩散率 D 的小颗粒扩散运动极限，给出了分析解。结果证实了在传播颗粒前沿动力学中局部极大值和极小值的建立。尽管特征线方法未能准确预测附近尖锐梯度处悬浮颗粒浓度，例如在某些注入情况下可以看到的颗粒前沿峰值处，但它可以成功预测颗粒运动和颗粒前沿的位置，在这种情况下，颗粒扩散不可避免地起着重要作用。研究结果为应用设计提供了信息，其中溶质梯度的应用可以极大地增强颗粒注入和从孔隙中抽取。
