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arXiv 2401.09461cond-mat.soft
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极性活性物质中的旋节线分解与相分离

Spinodal decomposition and phase separation in polar active matter

Maxx Miller, John Toner

AI总结:

本文提出结合自趋化性与集群流体动力学的理论,揭示极性活性物质中由自趋化性驱动的条带失稳与相分离机制,并阐明其稳态密度由非公切线构造决定,与无序活性粒子MIPS类似。

摘要:

我们建立并研究了具有自趋化性的集群流体动力学理论。该理论描述大量自推进实体自发地沿同一方向运动,每个实体释放一种吸引其他个体的物质(例如蚂蚁)。该理论结合了自趋化性的Keller-Segel模型与集群的Toner-Tu理论的特征。我们发现,足够强的自趋化性会导致均匀运动状态(“集群”)失稳,其中不同密度的条带以不同速度平行于平均集群速度运动。这些条带让人联想到蚂蚁路径,它们随时间粗化,最终达到相分离状态,此时一个高密度条带和一个低密度条带填满整个系统。同样的失稳,由同一流体动力学理论描述,可以发生在因任何微观机制(例如足够强的吸引相互作用)而发生相分离的集群中。尽管在许多方面类似于通过旋节线分解实现的平衡相分离,但这里的两个稳态密度并非像平衡态那样由公切线构造决定,而是由一种非公切线构造决定,该构造与无序活性粒子的运动诱导相分离(MIPS)中发现的构造非常相似。我们的解析理论与运动方程的数值模拟结果吻合良好。

英文摘要:

We develop and study the hydrodynamic theory of flocking with autochemotaxis. This describes large collections of self-propelled entities all spontaneously moving in the same direction, each emitting a substance which attracts the others (e.g., ants). The theory combines features of the Keller-Segel model for autochemotaxis with the Toner-Tu theory of flocking. We find that sufficiently strong autochemotaxis leads to an instability of the uniformly moving state (the ``flock"), in which bands of different density form moving parallel to the mean flock velocity with different speeds. These bands, which are reminiscent of ant trails, coarsen over time to reach a phase-separated state, in which one high density and one low density band fill the entire system. The same instability, described by the same hydrodynamic theory, can occur in flocks phase separating due to any microscopic mechanism (e.g., sufficiently strong attractive interactions). Although in many ways analogous to equilibrium phase separation via spinodal decomposition, the two steady state densities here are determined not by a common tangent construction, as in equilibrium, but by an uncommon tangent construction very similar to that found for motility induced phase separation (MIPS) of disordered active particles. Our analytic theory agrees well with our numerical simulations of our equations of motion.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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