Spontaneous Electrokinetic Magnus Effect.
Spontaneous Electrokinetic Magnus Effect.
复制标题
自发动电马格努斯效应。
DOI：
10.1103/physrevlett.124.208002
复制
发表时间：
2020
影响因子：
8.6
通讯作者：
J. Swan
中科院分区：
文献类型：
--
作者：
Z. Sherman;J. Swan
胶体分散在电解质中，暴露在电场中，在周围产生局部极化的离子云。在临界电场强度以上，发生不稳定性，导致这些离子云破坏对称性，导致粒子围绕与所施加的场正交的轴自发旋转，这种现象称为昆克旋转。在这封信中，我们描述了一种新的电动运输模式。如果胶体具有净电荷，则昆克旋转与电泳运动耦合，并在与所施加的场和旋转轴正交的方向上推进粒子。这种运动是一种自发的，电动类似于众所周知的马格努斯效应。通常，与场正交的运动需要粒子形状、介电性质或边界几何形状的各向异性。在这里，电动马格努斯（EKM）效应发生在无界环境中具有各向同性性质的球体上，昆克旋转不稳定性提供了驱动正交运动所需的对称性破缺。我们研究了EKM效应使用显式离子，布朗动力学模拟和发展一个简单的，连续的，分析电动力学理论，这是一致的。我们还解释了离子的理论描述中的非线性如何影响昆克旋转和EKM效应。
Colloids dispersed in electrolytes and exposed to an electric field produce a locally polarized cloud of ions around them. Above a critical electric field strength, an instability occurs causing these ion clouds to break symmetry leading to spontaneous rotation of particles about an axis orthogonal to the applied field, a phenomenon named Quincke rotation. In this Letter, we characterize a new mode of electrokinetic transport. If the colloids have a net charge, Quincke rotation couples with electrophoretic motion and propels particles in a direction orthogonal to both the applied field and the axis of rotation. This motion is a spontaneous, electrokinetic analogue to the well-known Magnus effect. Typically, motion orthogonal to a field requires anisotropy in particle shape, dielectric properties, or boundary geometry. Here, the electrokinetic Magnus (EKM) effect occurs for spheres with isotropic properties in an unbounded environment, with the Quincke rotation instability providing the broken symmetry needed to drive orthogonal motion. We study the EKM effect using explicit ion, Brownian dynamics simulations and develop a simple, continuum, analytic electrokinetic theory, which are in agreement. We also explain how nonlinearities in the theoretical description of the ions affect Quincke rotation and the EKM effect.