发表机构
Niels Bohr Institute, University of Copenhagen（尼尔斯·玻尔研究所，哥本哈根大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过Floquet线性稳定性分析揭示活性向列相中涡旋状态源于二次之字形不稳定性，无需非线性机制，并在通道约束下预测涡旋数量，为实验验证提供途径。
AI 中文摘要
活性物质研究中的一个标志性结果是自发流动不稳定性，通过这种不稳定性，均匀排列的状态沿单一方向打破平移对称性并发展出持续流动。在更高活性下出现的涡旋状态则被归因于非线性动力学。利用Floquet型线性稳定性分析，我们表明不需要这样的机制：流动状态经历二次之字形不稳定性，打破剩余的平移对称性并产生涡旋状态。我们进一步确定了一个区域，在该区域中流动状态不再存在，涡旋直接从均匀排列状态出现。在通道约束下，不稳定性选择了一个与已建立的活性长度尺度不同的长度尺度，并设定了出现的涡旋数量，导致一种类似涡旋晶格的约束选择图案，为直接实验测试这种不稳定性开辟了途径。完整的非线性模拟再现了预测的起始活性和选定的涡旋数量。
英文摘要
One of the defining results in the study of active matter is the spontaneous flow instability, through which a homogeneous, uniformly aligned state breaks translational symmetry along a single direction and develops sustained flow. The vortex state that emerges at higher activity has instead been attributed to nonlinear dynamics. Using a Floquet-type linear stability analysis, we show that no such mechanism is required: the flowing state undergoes a secondary, zigzag instability that breaks the remaining translational symmetry and produces the vortex state. We further identify a regime in which the flowing state ceases to exist and vortices emerge directly from the uniformly aligned state. Under channel confinement, the instability selects a length scale that differs from the establishedactivelengthscale, andsetsthenumberofvorticesthatappear, leadingtoaconfinement- selected pattern reminiscent of a vortex lattice, opening a route toward direct experimental tests of this instability. Full nonlinear simulations reproduce the predicted onset activities and the selected vortex number.
Comments7 pages, 3 figures
