Dynamics of a simple model microswimmer in an anisotropic fluid: Implications for alignment behavior and active transport in a nematic liquid crystal
Dynamics of a simple model microswimmer in an anisotropic fluid: Implications for alignment behavior and active transport in a nematic liquid crystal
复制标题
DOI：
10.1103/physrevfluids.3.094102
复制
发表时间：
2018-09-27
影响因子：
2.7
通讯作者：
Menzel, Andreas M.
中科院分区：
文献类型：
--
作者：
Daddi-Moussa-Ider, Abdallah;Menzel, Andreas M.
最近的几个实验研究了自驱动细菌和胶体粒子在液晶中的取向和传输行为。相应地，我们从理论上研究了单轴各向异性流体中最小模型微游泳者的动力学。作为第一步，流体动力学的绿色的功能，提供响应于作用在各向异性流体上的局部化的力的流体流动解析地导出。在此基础上，分析了拉式和推式微泳子在各向异性流体中的行为。根据推进机制和不同的粘度的相对大小，我们发现对齐的游泳者平行或垂直于各向异性轴。特别地，在某些情况下也识别倾斜对准。所观察到的游泳者重新取向的结果之间的流体动力学耦合的自诱导流体流动和周围流体的各向异性，这扭曲了自生流场。我们支持我们的结果的一个简化的线性稳定性分析。我们的理论预测与最近对向列型液晶中游动细菌的实验观察定性一致。它们支持利用宿主流体的可能可切换的各向异性来引导个体微泳者和活性颗粒沿着所请求的路径的目的，从而实现受控的主动运输。
Several recent experiments investigate the orientational and transport behavior of self-driven bacteria and colloidal particles in nematic liquid crystals. Correspondingly, we study theoretically the dynamics of a minimal model microswimmer in a uniaxially anisotropic fluid. As a first step, the hydrodynamic Green's function providing the resulting fluid flow in response to a localized force acting on the anisotropic fluid is derived analytically. On this basis, the behavior of both puller- and pusher-type microswimmers in the anisotropic fluid is analyzed. Depending on the propulsion mechanism and the relative magnitude of different involved viscosities, we find alignment of the swimmers parallel or perpendicular to the anisotropy axis. Particularly, also an oblique alignment is identified under certain circumstances. The observed swimmer reorientation results from the hydrodynamic coupling between the self-induced fluid flow and the anisotropy of the surrounding fluid, which distorts the self-generated flow field. We support parts of our results by a simplified linear stability analysis. Our theoretical predictions are in qualitative agreement with recent experimental observations on swimming bacteria in nematic liquid crystals. They support the objective of utilizing the possibly switchable anisotropy of a host fluid to guide individual microswimmers and active particles along a requested path, enabling controlled active transport.