发表机构
Otto-von-Guericke-Universität Magdeburg（马格德堡奥托·冯·格里克大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究扩展流体粒子动力学方法至黏弹性和弹性介质，研究主动微流变中探针粒子的线性和非线性响应，发现非线性效应导致粒子漂移，与实验设置相符。
AI 中文摘要
主动微流变学是一种有效的工具，用于在微观尺度上确定黏性、黏弹性或弹性材料的流变性质。嵌入的探针粒子对外部施加的振荡驱动力的位置响应，可以间接表征周围介质的性质。我们旨在探索平面几何微流变装置中探针粒子的线性和非线性响应。为此，我们将流体粒子动力学的计算方法从黏性流体状介质扩展到黏弹性和弹性介质，包括非线性区域。我们考虑由固体壁限制的系统。在这种情况下，我们通过量化基于Jeffreys模型的线性响应来验证该方法。增加驱动力的振幅，我们观察到明显的非线性效应。这些效应包括畸变的应力-应变曲线以及初始位于壁附近的探针粒子的逐渐净漂移。这种漂移在黏性流体状和弹性固体状极限中消失，但在中间黏弹性系统中表现明显。我们进一步处理了没有壁的两个探针粒子的设置。它们经历相互的成对振荡强迫。在这里，黏弹性系统中的非线性效应诱导净漂移，逐渐使粒子彼此远离。与真实设置相比，我们驱动力的实现与光镊或主动磁微流变的实验设置一致。
英文摘要
Active microrheology is an effective tool to determine the rheological properties of viscous, viscoelastic, or elastic materials on microscopic length scales. The positional response of an embedded probe particle to an externally applied oscillating driving force allows to indirectly characterize the properties of the surrounding media. We aim to explore the linear and nonlinear response of probe particles in a microrheological setup of planar geometry. For this purpose, we extend the computational method of fluid particle dynamics from viscous fluid-like to viscoelastic and elastic media, including nonlinear regimes. We consider a system confined by solid walls. In this case, we validate the approach by quantifying the linear response in terms of a Jeffreys model. Increasing the amplitude of the driving force, we observe distinct nonlinear effects. They include distorted stress-strain curves and a gradual net drift of probe particles initially positioned close to a wall. This drift vanishes in the viscous fluid-like and elastic solid-like limits, but is manifest for intermediate viscoelastic systems. We further address a setup of two probe particles in the absence of walls. They experience reciprocal pairwise oscillatory forcing. Here, nonlinearities in viscoelastic systems induce a net drift gradually moving the particles further apart from each other. Comparing with real setups, our implementation of the driving force is in line with experimental setups of optical tweezers or active magnetic microrheology.
