过阻尼胶体动力学中的流体动力学记忆
Hydrodynamic memory in overdamped colloidal dynamics
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中文总结 AI 辅助
本研究证明过阻尼极限下胶体扩散仍保留流体动力学记忆，推导出含记忆的过阻尼朗之万方程，预测小粒子与强外力下记忆更显著，为高分辨率实验提供理论框架。
中文摘要 AI 辅助
微米级胶体粒子在流体中扩散时会经历流体动力学惯性效应和记忆效应，后者导致速度自相关函数按幂律衰减。与此同时，许多理论描述为了方便，使用过阻尼朗之万动力学来处理流体中的胶体扩散，从而消除了速度、忽略了惯性，但也忽略了幂律记忆。在本快报中，我们证明流体动力学记忆在过阻尼（胶体无惯性）极限下仍然存在。通过识别控制早期与晚期动力学之间交叉的无量纲参数，我们以闭式形式推导了存在流体动力学记忆时的过阻尼朗之万方程。这为真实描述流体中的胶体动力学提供了理论框架，并为高分辨率实验中观测到的位置记忆建立了严格基础。我们的理论预测，对于更小的粒子和更强的外部强迫，流体动力学记忆变得更加显著，并为从传统指数弛豫到记忆主导的幂律动力学的交叉提供了实验探测手段。
英文摘要
Micron-sized colloid particles diffusing through a fluid experience hydrodynamic inertial and memory effects, the latter causing velocity autocorrelation to decay as a power law. At the same time, many theoretical descriptions treat colloidal diffusion in a fluid using overdamped Langevin dynamics for its convenience, eliminating velocity, omitting inertia, but also ignoring the power-law memory. In this Letter, we show that hydrodynamic memory survives in the overdamped (colloid-inertialess) limit. By identifying the dimensionless parameter controlling the crossover between early- and late-time dynamics, we derive in closed form the overdamped Langevin equation in the presence of hydrodynamic memory. This provides a theoretical framework for realistically describing colloidal dynamics in a fluid, and establishes a rigorous basis for the positional memory observed in high-resolution experiments. Our theory predicts that hydrodynamic memory becomes increasingly pronounced for smaller particles and under stronger external forcing, and offers experimental probes for the crossover from conventional exponential relaxation to memory-dominated power-law dynamics.
发表机构
- Princeton Center for Theoretical Science, Princeton University（普林斯顿大学理论物理中心）
- Princeton Materials Institute, Princeton University（普林斯顿大学材料研究所）
- Department of Mechanical and Aerospace Engineering, Princeton University（普林斯顿大学机械与航空航天工程系）
机构由 AI 辅助整理，请以论文原文为准。
