论文标题
活性极性流体与主动命名的缺陷动力学
Defect Dynamics in Active Polar Fluids vs. Active Nematics
论文作者
论文摘要
拓扑缺陷在二维活性列表中起关键作用，并且在二维活动极性流体中起瞬时作用。在本文中，我们研究了二维活性极性流体中缺陷的瞬时和长时间行为，并以强阶的极限和过度低阻压，可压缩流量，并将缺陷动力学与最近研究的相应的活动性nematics模型进行比较。结果之一是缺陷对活性极性流体之间的非中心相互作用，并且通过扩展我们的分析以允许缺陷的方向动力学，我们发现$+1 $缺陷的方向（与$ \ pm 1/2 $的缺陷相比，主动nematics中的缺陷都不是锁定缺陷的位置和放松的位置，并放宽了ASTES的一个。此外，使用缩放参数，我们解释了活动极性缺陷的瞬态特征，并表明在稳态，活性极性流体要么没有缺陷，要么由单个紫外线组成。我们认为，对于收缩（扩大）主动列表系统，$+1 $涡流（Asters）应成为最近观察到的一对$+1/2 $缺陷的界面。此外，与极地情况不同，我们表明，对于主动命名，$+1/2 $缺陷的对差距的绑定状态相同的线性链可以筛选活动术语。这两个模型中的一个共同特征是稳定状态下的$+1 $缺陷（在北极和近极中的基本和复合）的外观。
Topological defects play a key role in two-dimensional active nematics, and a transient role in two-dimensional active polar fluids. In this paper, we study both the transient and long-time behavior of defects in two-dimensional active polar fluids in the limit of strong order and overdamped, compressible flow, and compare the defect dynamics with the corresponding active nematics model studied recently. One result is non-central interactions between defect pairs for active polar fluids, and by extending our analysis to allow orientation dynamics of defects, we find that the orientation of $+1$ defects, unlike that of $\pm 1/2$ defects in active nematics, is not locked to defect positions and relaxes to asters. Moreover, using a scaling argument, we explain the transient feature of active polar defects and show that in the steady state, active polar fluids are either devoid of defects or consist of a single aster. We argue that for contractile (extensile) active nematic systems, $+1$ vortices (asters) should emerge as bound states of a pair of $+1/2$ defects, which has been recently observed. Moreover, unlike the polar case, we show that for active nematics, a linear chain of equally spaced bound states of pairs of $+1/2$ defects can screen the activity term. A common feature in both models is the appearance of $+1$ defects (elementary in polar and composite in nematic) in the steady state.
