Nematohydrodynamics for colloidal self-assembly and transport phenomena.
Nematohydrodynamics for colloidal self-assembly and transport phenomena.
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DOI：
10.1016/j.jcis.2018.05.072
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发表时间：
2017-07
影响因子：
9.9
通讯作者：
S. Mondal;A. Majumdar;I. Griffiths
中科院分区：
文献类型：
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作者：
S. Mondal;A. Majumdar;I. Griffiths
假设向列型液晶(NLC)中的胶体颗粒表现出与在各向同性介质中观察到的非常不同的行为。这些差异主要是由于NLC分子与界面的相互作用而产生的向列相诱导的弹性应力，这与传统的施加在粒子上的流体粘性应力相互竞争。理论利用耦合到Navier-Stokes方程的连续介质Beris-Edwards框架对NLC微流体通道中的粒子进行了系统的数学分析。我们在流道壁上施加强同向力锚定，在颗粒表面施加弱同向力锚定。发现粘性力和NLC力以相反的方向作用于单个颗粒，导致在通道中颗粒在垂直于流动的方向上的净力为零的关键位置。对于多粒子聚集，我们证明了最终的排列与初始构型无关，但达到平衡的路径是非常不同的。这些结果揭示了粒子分离的新机制和自组装的途径。
HypothesisColloidal particles in a nematic liquid crystal (NLC) exhibit very different behaviour to that observed in an isotropic medium. Such differences arise principally due to the nematic-induced elastic stresses exerted due to the interaction of NLC molecules with interfaces, which compete with traditional fluid viscous stresses on the particle.TheoryA systematic mathematical analysis of particles in an NLC microfluidic channel is performed using the continuum Beris–Edwards framework coupled to the Navier–Stokes equations. We impose strong homeotropic anchoring on the channel walls and weak homeotropic anchoring on the particle surfaces.FindingsThe viscous and NLC forces act on an individual particle in opposing directions, resulting in a critical location in the channel where the particle experiences zero net force in the direction perpendicular to the flow. For multi-particle aggregation we show that the final arrangement is independent of the initial configuration, but the path towards achieving equilibrium is very different. These results uncover new mechanisms for particle separation and routes towards self-assembly.