Non-equilibrium electric double layers in narrow channels

本文从Poisson方程、Nernst-Planck方程、热输运方程和Stokes方程出发，研究了电解质填充窄通道内双电层的非平衡效应。首先，将研究轴向温度梯度对充满电解质的狭缝通道的影响。将根据基本方程组的渐近展开式计算由于EDL中的热致力不平衡引起的流场。还将考虑温度依赖性壁zeta电位的影响。除了方程的分析处理，数值解将被用来测试分析模型的有效性范围，并探索超出这个政权的参数空间。第二，探讨在通道壁上的化学反应对电渗流的影响。当新鲜电解质通过平流引入通道时，壁处的化学平衡被扰乱，可能导致zeta电位的动态变化。将根据从通道横截面平均获得的降阶模型来研究这种效应及其对湍流的影响。本说明书将结合一个简单的模型的壁反应和面积平均传输项的扩散，平流和电迁移的离子。该模型的参数研究将伴随着实验，在实验中，测量作为时间函数的微扰速度。在申请人的小组中进行的第一个实验已经表明，壁zeta电位可能是受通道内的电荷影响的动态量。

Non-equilibrium effects in electric double layers (EDLs) inside narrow electrolyte-filled channels will be studied theoretically based on the combined Poisson, Nernst-Planck, heat transport and Stokes equations. Firstly, the effects of an axial temperature gradient on an electrolyte-filled slit-channel will be investigated. The flow field due to the thermally-induced force imbalance in the EDL will be computed based on asymptotic expansions of the underlying system of equations. The effect of a temperature dependent wall zeta potential will also be considered. Apart from the analytical treatment of the equations, numerical solutions will be employed to test the range of validity of the analytical model and to explore the parameter space beyond this regime. Secondly, the influence of chemical reactions at the channel walls on electroosmotic flow (EOF) will be explored. When fresh electrolyte is introduced into a channel via advection, the chemical equilibrium at the walls is disturbed, potentially resulting in dynamic changes of the zeta potential. This effect and its influence on EOF will be studied based on a reduced-order model obtained from averaging over the channel cross section. The description will incorporate a simple model for the wall reactions and area-averaged transport terms for the diffusion, advection and electromigration of ions. The parameter studies with this model will be accompanied by experiments in which the EOF velocity as a function of time is measured. First experiments conducted in the group of the applicant have already indicated that the wall zeta potential may be a dynamic quantity influenced by the EOF inside the channel.