Thijssen Kristian, Metselaar Luuk, Yeomans Julia M, Doostmohammadi Amin
The Rudolf Peierls Centre for Theoretical Physics, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen, Denmark.
Soft Matter. 2020 Feb 26;16(8):2065-2074. doi: 10.1039/c9sm01963d.
We use continuum simulations to study the impact of anisotropic hydrodynamic friction on the emergent flows of active nematics. We show that, depending on whether the active particles align with or tumble in their collectively self-induced flows, anisotropic friction can result in markedly different patterns of motion. In a flow-aligning regime and at high anisotropic friction, the otherwise chaotic flows are streamlined into flow lanes with alternating directions, reproducing the experimental laning state that has been obtained by interfacing microtubule-motor protein mixtures with smectic liquid crystals. Within a flow-tumbling regime, however, we find that no such laning state is possible. Instead, the synergistic effects of friction anisotropy and flow tumbling can lead to the emergence of bound pairs of topological defects that align at an angle to the easy flow direction and navigate together throughout the domain. In addition to confirming the mechanism behind the laning states observed in experiments, our findings emphasise the role of the flow aligning parameter in the dynamics of active nematics.
我们使用连续介质模拟来研究各向异性流体动力摩擦对活性向列相涌现流的影响。我们表明，取决于活性粒子是在其集体自诱导流中排列还是翻滚，各向异性摩擦会导致明显不同的运动模式。在流动排列 regime 且具有高各向异性摩擦时，原本混沌的流会被简化为具有交替方向的流道，重现了通过将微管 - 马达蛋白混合物与近晶液晶界面接触而获得的实验流道状态。然而，在流动翻滚 regime 内，我们发现不存在这样的流道状态。相反，摩擦各向异性和流动翻滚的协同效应可导致出现成对的拓扑缺陷，这些缺陷与易流动方向成一定角度排列并在整个区域内一起移动。除了证实实验中观察到的流道状态背后的机制外，我们的发现还强调了流动排列参数在活性向列相动力学中的作用。
