Single-particle diffusion in dense inhomogeneous colloid suspensions in ribbon channels.
Single-particle diffusion in dense inhomogeneous colloid suspensions in ribbon channels.
复制标题
带状通道中致密不均匀胶体悬浮液中的单颗粒扩散。
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
S. Rice
中科院分区：
文献类型：
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作者：
Emily A. Wonder;B. Lin;S. Rice
我们报告了限制在准维 (q1D) 和准二维 (q2D) 之间的带状通道几何形状中的稠密胶体流体中单粒子扩散的研究结果。本文补充了之前关于同一系统中对扩散的论文 [Phys.修订版 E 82, 031403 (2010)]。在所有研究的系统中，横向于带状通道的胶体密度分布是分层的，峰值幅度取决于胶体密度。虽然限制层的虚拟壁的结构具有胶体直径的尺度长度，但该结构对单粒子扩散没有明显影响，这显示了具有光滑壁的 q1D 通道中扩散的特征。我们发现，对于所研究的所有通道宽度和堆积分数，地层中的单颗粒横向扩散系数小于同一地层中的单颗粒纵向扩散系数，并且地层之间的单颗粒纵向扩散系数变化很小，仅在靠近壁的致密地层中比在中心地层中稍小。纵向扩散系数随表观地层密度变化的缺乏可以通过将 Fischer-Methfessel 近似应用于不均匀液体中的局部密度来解释。横向与纵向扩散系数之比随带宽度变化非常缓慢，这意味着从 q1D 到 q2D 行为的转变非常缓慢。
We report the results of a study of single-particle diffusion in dense colloid fluids confined in a ribbon channel geometry that is intermediate between quasione dimensional (q1D) and quasitwo dimensional (q2D). This paper complements a previous paper about pair diffusion in the same system [Phys. Rev. E 82, 031403 (2010)]. In all of the systems studied, the colloid density distribution transverse to the ribbon channel is stratified with peak amplitudes that depend on the colloid density. Although the virtual walls that confine a stratum are structured with a scale length of the colloid diameter, that structure does not have an apparent influence on the single-particle diffusion, which shows the characteristic features of diffusion in a q1D channel with smooth walls. We find that, for all channel widths and packing fractions studied, the single-particle transverse diffusion coefficient in a stratum is smaller than the single-particle longitudinal diffusion coefficient in the same stratum and that the single-particle longitudinal diffusion coefficient varies very little from stratum to stratum, being only slightly smaller in the dense strata next to the walls than in the central strata. The lack of variation in the longitudinal diffusion coefficient with apparent stratum density is explained by the application of the Fischer-Methfessel approximation to the local density in an inhomogeneous liquid. The ratio of the transverse to longitudinal diffusion coefficients varies very slowly with ribbon width, implying a very slow transition from q1D to q2D behavior.