Mesoscale pattern formation of self-propelled rods with velocity reversal
Mesoscale pattern formation of self-propelled rods with velocity reversal
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DOI：
10.1103/physreve.94.050602
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发表时间：
2016-11-22
影响因子：
2.4
通讯作者：
Baer, Markus
中科院分区：
文献类型：
--
作者：
Grossmann, Robert;Peruani, Fernando;Baer, Markus
我们研究了自推进粒子与速度反转相互作用的单轴（单轴）排列内的粗粒度流体动力学理论。结合分析和数值延拓技术，我们表明，这个活跃的系统的物理本质上是由反转频率控制。特别是，我们发现，细长的，高密度的，有序的模式，所谓的带，出现通过亚临界分叉从空间均匀的状态。我们的分析进一步揭示了带的相互作用是弱吸引力的，因此，带融合碰撞在类比非平衡成核过程。此外，我们证明了一个重整化的积极的线张力可以分配到稳定的带低于临界反转率，超过这个临界反转率，他们是横向不稳定的。此外，我们还讨论了带的动力学粗化以及在横向不稳定性阈值附近的非线性动力学。总之，减少的多粒子系统的动态带提供了一个统一的框架来理解的出现和稳定的非平衡模式，在这个自推进的粒子系统。在这方面，我们的研究结果构成了有利于微生物学假设的原则证明，即滑杆形细菌的速度逆转调节细菌生命周期中观察到的各种自组织模式之间的转换。
We study self-propelled particles with velocity reversal interacting by uniaxial (nematic) alignment within a coarse-grained hydrodynamic theory. Combining analytical and numerical continuation techniques, we show that the physics of this active system is essentially controlled by the reversal frequency. In particular, we find that elongated, high-density, ordered patterns, called bands, emerge via subcritical bifurcations from spatially homogeneous states. Our analysis reveals further that the interaction of bands is weakly attractive and, consequently, bands fuse upon collision in analogy with nonequilibrium nucleation processes. Moreover, we demonstrate that a renormalized positive line tension can be assigned to stable bands below a critical reversal rate, beyond which they are transversally unstable. In addition, we discuss the kinetic roughening of bands as well as their nonlinear dynamics close to the threshold of transversal instability. Altogether, the reduction of the multiparticle system onto the dynamics of bands provides a unified framework to understand the emergence and stability of nonequilibrium patterns in this self-propelled particle system. In this regard, our results constitute a proof of principle in favor of the hypothesis in microbiology that velocity reversal of gliding rod-shaped bacteria regulates the transitions between various self-organized patterns observed during the bacterial life cycle.