Li Dongdong, Liu Yanan, Luo Hao, Jing Guangyin
School of Physics, Northwest University, Xi'an 710127, China.
Micromachines (Basel). 2024 Jan 28;15(2):199. doi: 10.3390/mi15020199.
The study of particle diffusion, a classical conundrum in scientific inquiry, holds manifold implications for various real-world applications. Particularly within the domain of active flows, where the motion of self-propelled particles instigates fluid movement, extensive research has been dedicated to unraveling the dynamics of passive spherical particles. This scrutiny has unearthed intriguing phenomena, such as superdiffusion at brief temporal scales and conventional diffusion at longer intervals. In contrast to the spherical counterparts, anisotropic particles, which manifest directional variations, are prevalent in nature. Although anisotropic behavior in passive fluids has been subject to exploration, enigmatic aspects persist in comprehending the interplay of anisotropic particles within active flows. This research delves into the intricacies of anisotropic passive particle diffusion, exposing a notable escalation in translational and rotational diffusion coefficients, as well as the superdiffusion index, contingent upon bacterial concentration. Through a detailed examination of particle coordinates, the directional preference of particle diffusion is not solely dependent on the particle length, but rather determined by the ratio of the particle length to the associated length scale of the background flow field. These revelations accentuate the paramount importance of unraveling the nuances of anisotropic particle diffusion within the context of active flows. Such insights not only contribute to the fundamental understanding of particle dynamics, but also have potential implications for a spectrum of applications.
粒子扩散的研究是科学探究中的一个经典难题，对各种实际应用具有多方面的意义。特别是在主动流领域，自推进粒子的运动会引发流体运动，大量研究致力于揭示被动球形粒子的动力学。这种研究揭示了一些有趣的现象，比如在短时间尺度上的超扩散和较长时间间隔下的常规扩散。与球形粒子不同，表现出方向变化的各向异性粒子在自然界中很普遍。虽然被动流体中的各向异性行为已得到探索，但在理解主动流中各向异性粒子的相互作用方面仍存在一些神秘之处。这项研究深入探讨了各向异性被动粒子扩散的复杂性，发现随着细菌浓度的变化，平动和转动扩散系数以及超扩散指数都有显著增加。通过对粒子坐标的详细研究，粒子扩散的方向偏好不仅取决于粒子长度，还由粒子长度与背景流场相关长度尺度的比值决定。这些发现凸显了在主动流背景下揭示各向异性粒子扩散细微差别的至关重要性。这些见解不仅有助于对粒子动力学的基本理解，也对一系列应用具有潜在意义。
