This work presents a theoretical and numerical study of electrokinetic flow and the zeta potential for the case of slit channels with nanoscale roughness of dimensions comparable to the Debye length, by employing molecular dynamics simulations and continuum-level analyses. A simple analytical model for considering the effects of the surface roughness is proposed by employing matched asymptotic solutions for the charge density and fluid flow field, and matching conditions that satisfy electroneutrality and the Onsager reciprocal relation between the electroosmotic flow rate and streaming current. The proposed analytical model quantitatively accounts for results from molecular dynamics simulations that consider the presence of ion solvation shells and surface hydration layers. Our analysis indicates that a simultaneous knowledge of the electroosmotic and pressure-driven flow rate or streaming current can be instrumental to determine unambiguously the zeta potential and the characteristic surface roughness height.

中文翻译：

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纳米结构狭缝通道中电动 zeta 电位的分子动力学和连续谱分析

这项工作通过采用分子动力学模拟和连续谱级分析，对具有与德拜长度相当的纳米级粗糙度的狭缝通道的情况下的电动流动和 zeta 电位进行了理论和数值研究。通过采用电荷密度和流体流场的匹配渐近解，以及满足电中性和电渗流速与流动电流之间的 Onsager 倒数关系的匹配条件，提出了一个考虑表面粗糙度影响的简单分析模型。所提出的分析模型定量地解释了分子动力学模拟的结果，该模拟考虑了离子溶剂化壳和表面水化层的存在。