We report that an electro-osmotic instability of concentration enrichment in curved geometries for an aqueous electrolyte, as opposed to the well-known one, is initiated exclusively at the enriched interface (anode), rather than at the depleted one (cathode). For this instability, the limitation of an unrealistically high material Peclet number in planar geometry is eliminated by the strong electric field arising from the line charge singularity. In a model setup of concentric circular electrodes, we show by stability analysis, numerical simulation, and experimental visualization that instability occurs at the inner anode, below a critical radius of curvature. The stability criterion is also formulated in terms of a critical electric field and extended to arbitrary (two-dimensional) geometries by conformal mapping. This discovery suggests that transport may be enhanced in processes limited by salt enrichment, such as reverse osmosis, by triggering this instability with needlelike electrodes.

中文翻译：

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水溶液中弯曲几何形状中浓度富集的电渗不稳定性

我们报告说，与众所周知的水溶液相反，水溶液电解质在弯曲几何形状中浓度富集的电渗不稳定性仅在富集界面（阳极）而不是贫化界面（阴极）引发。对于这种不稳定性，通过线电荷奇异性产生的强电场消除了平面几何形状中不切实际的高材料Peclet数的限制。在同心圆形电极的模型设置中，我们通过稳定性分析，数值模拟和实验可视化显示，在临界曲率半径以下，内部阳极发生不稳定性。还根据临界电场来制定稳定性标准，并通过保形映射将其扩展到任意（二维）几何形状。