School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Department of Mathematics, The University of Akron, Akron, Ohio 44325, USA.
Phys Rev E. 2018 Aug;98(2-1):022703. doi: 10.1103/PhysRevE.98.022703.
Electrokinetic phenomena in a nematic suspension are considered when one or more dielectric particles are suspended in a liquid crystal matrix in its nematic phase. The long-range orientational order of the nematic constitutes a fluid with anisotropic properties. This anisotropy enables charge separation in the bulk under an applied electric field, and leads to streaming flows even when the applied field is oscillatory. In the cases considered, charge separation is seen to result from director field distortions in the matrix that are created by the suspended particles. We use a recently introduced electrokinetic model to study the motion of a single-particle hyperbolic hedgehog pair. We find this motion to be parallel to the defect-particle center axis, independent of field orientation. For a two-particle configuration, we find that the relative force of electrokinetic origin is attractive in the case of particles with perpendicular director anchoring, and repulsive for particles with tangential director anchoring. The study reveals large scale flow properties that are respectively derived from the topology of the configuration alone and from short scale hydrodynamics phenomena in the vicinity of the particle and defect.
当一个或多个介电粒子悬浮在各向异性液晶基质的向列相中时，会出现向列悬浮体中的电动现象。向列相的长程取向有序构成了具有各向异性性质的流体。这种各向异性使得在施加电场时在体内发生电荷分离，并导致即使施加的场是振荡的也会产生流动。在所考虑的情况下，电荷分离被认为是由悬浮粒子在基质中产生的指向矢场畸变引起的。我们使用最近引入的电动模型来研究单个双曲 hedgehog 对的运动。我们发现这种运动与缺陷粒子的中心轴平行，与场的方向无关。对于双粒子配置，我们发现对于具有垂直指向矢锚定的粒子，电动起源的相对力是吸引力，而对于具有切向指向矢锚定的粒子，则是排斥力。研究揭示了大尺度流动特性，这些特性分别仅源自于配置的拓扑结构和粒子及缺陷附近的短尺度流体力学现象。
