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Crowding-Enhanced Diffusion: An Exact Theory for Highly Entangled Self-Propelled Stiff Filaments
arXiv - PHYS - Soft Condensed Matter Pub Date : 2022-09-21 , DOI: arxiv-2209.10237
Suvendu Mandal, Christina Kurzthaler, Thomas Franosch, Hartmut Löwen

We study a strongly interacting crowded system of self-propelled stiff filaments by event-driven Brownian dynamics simulations and an analytical theory to elucidate the intricate interplay of crowding and self-propulsion. We find a remarkable increase of the effective diffusivity upon increasing the filament number density by more than one order of magnitude. This counter-intuitive 'crowded is faster' behavior can be rationalized by extending the concept of a confining tube pioneered by Doi and Edwards for highly entangled crowded, passive to active systems. We predict a scaling theory for the effective diffusivity as a function of the P\'eclet number and the filament number density. Subsequently, we show that an exact expression derived for a single self-propelled filament with motility parameters as input can predict the non-trivial spatiotemporal dynamics over the entire range of length and time scales. In particular, our theory captures short-time diffusion, directed swimming motion at intermediate times, and the transition to complete orientational relaxation at long times.

中文翻译:

拥挤增强扩散:高度缠结自走硬丝的精确理论

我们通过事件驱动的布朗动力学模拟和分析理论研究了一个强烈相互作用的自推进刚性细丝拥挤系统,以阐明拥挤和自推进之间复杂的相互作用。我们发现当灯丝数量密度增加一个数量级以上时,有效扩散率显着增加。这种反直觉的“拥挤是更快”的行为可以通过扩展 Doi 和 Edwards 为高度纠缠拥挤、被动到主动系统的限制管的概念来合理化。我们预测了作为 P'eclet 数和灯丝数密度函数的有效扩散率的比例理论。随后,我们表明,以运动参数作为输入的单个自推进灯丝的精确表达式可以预测整个长度和时间尺度范围内的非平凡时空动态。特别是,我们的理论捕捉了短时间扩散、中间时间的定向游泳运动以及长时间向完全定向松弛的过渡。
更新日期:2022-09-22
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