发表机构
Northwestern University（西北大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过线性稳定性、本征谱和机械功分析，揭示了粘弹性电解质中电对流不稳定性对Wi的非单调依赖，其机制由应力-变形相位关系、溶剂耗散和本征模态选择共同决定。
AI 中文摘要
离子选择性表面附近的电对流（EC）不稳定性在超越扩散限制区的电化学输运中起着关键作用。尽管牛顿电解质中的EC不稳定性已被广泛研究，但粘弹性对不稳定性机制的影响仍知之甚少。在本研究中，我们利用线性稳定性、本征谱和机械功分析，并辅以渐近路径排序，研究了粘弹性对EC不稳定性的调制。分析揭示了不稳定性对韦森伯格数Wi的非单调依赖，最大增长率和最小临界电压出现在Wi ~ O(1)附近。机械功平衡将电、溶剂粘性和聚合物贡献分开，并根据其本构来源进一步将聚合物功分解为法向应力差和剪切应力路径。对于Wi << 1，聚合物应力在前导阶恢复牛顿粘性耗散。当Wi趋近于1时，类牛顿聚合物路径的相位效率显著降低，导致负聚合物功崩溃，不稳定性增强。在中等Wi下，临界电压在低波数处出现额外的极小值。本征谱分析将此特征归因于一个缓慢传播模态的选择，该模态保留了大量的负聚合物功。在大Wi下，该模态不再决定不稳定性阈值，低波数极小值消失。法向应力差功和剪切应力功随后几乎抵消，伴随着更强的ESC局部剪切变形和主要溶剂粘性耗散。因此，非单调响应由应力-变形相位关系、溶剂耗散和本征模态选择控制，而非应力大小或单一聚合物贡献。
英文摘要
Electroconvective (EC) instability near ion-selective surfaces plays a key role in electro-chemical transport beyond the diffusion-limited regime. While EC instability in Newtonian electrolytes has been extensively investigated, the influence of viscoelasticity on the instability mechanism remains less understood. In the present study, we investigate the viscoelastic modulation of EC instability using linear stability, eigenspectrum, and mechanical-work analyses, supported by asymptotic pathway ordering. The analysis reveals a non-monotonic dependence on the Weissenberg number Wi, with the maximum growth rate and minimum critical voltage occurring near Wi ~ O(1). The mechanical-work balance separates electric, solvent-viscous, and polymeric contributions, and further decomposes the polymeric work into normal-stress-difference and shear-stress pathways according to their constitutive origins. For Wi << 1, the polymer stress recovers Newtonian viscous dissipation at leading order. As Wi approaches unity, the phase efficiencies of the Newtonian-like polymeric pathways decrease substantially, causing the negative polymeric work to collapse and the instability to intensify. At intermediate Wi, an additional minimum in the critical voltage appears at low wavenumbers. Eigenspectrum analysis attributes this feature to the selection of a slowly propagating mode that retains substantial negative polymeric work. At large Wi, this mode no longer determines the instability threshold, and the low-wavenumber minimum disappears. The normal-stress-difference and shear-stress work then nearly cancel, accompanied by stronger ESC-localized shear deformation and predominantly solvent-viscous dissipation. Thus, the non-monotonic response is governed by stress-deformation phase relations, solvent dissipation, and eigenmode selection rather than stress magnitude or a single polymeric contribution.
