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arXiv 2404.19085cond-mat.soft
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含时力作用下的非线性微流变学——在粘弹性流体中回弹现象的应用

Nonlinear microrheology with time-dependent forces -- Application to recoils in viscoelastic fluids

Nikolas Ditz, Antonio M. Puertas, M. Fuchs

AI总结:

本文将模耦合理论推广至含时力情形,结合朗之万模拟研究粘弹性流体中示踪胶体在关断力后的回弹行为,发现回弹幅度随力呈非单调变化,并验证了线性响应近似。

摘要:

本工作对示踪胶体在含时力驱动下穿过粘弹性流体的运动进行了理论分析。研究确定了胶体在受到强力作用后的回弹行为,这为理解流体中局部储存的弹性力及其因塑性过程而减弱提供了见解。我们将微流变学的模耦合理论推广到包含含时力的情况。在推导出示踪粒子关联函数的运动方程并简化为一个示意模型后,我们将该理论应用于一个关断力协议,该协议体现了驱动停止后示踪粒子的回弹。我们还引入朗之万动力学模拟与理论结果进行比较。理论中发现回弹幅度呈非单调趋势,并在模拟中得到证实。线性响应近似在小力区域也得到了验证。虽然模拟与理论总体吻合良好,但模拟表明理论预测的回弹距离对施加力的非单调依赖过强。

英文摘要:

This work presents a theoretical analysis of the motion of a tracer colloid driven by a time-dependent force through a viscoelastic fluid. The recoil of the colloid after application of a strong force is determined. It provides insights into the elastic forces stored locally in the fluid and their weakening by plastic processes. We generalize the mode coupling theory of microrheology to include time-dependent forces. After deriving the equations of motion for the tracer correlator and simplifying to a schematic model we apply the theory to a switch-off force protocol that features the recoiling of the tracer after cessation of the driving. We also include Langevin dynamics simulations to compare to the results of the theory. A non-monotonic trend of the recoil amplitude is found in the theory and confirmed in the simulations. The linear-response approximation is also verified in the small-force regime. While the overall agreement between simulation and theory is good, simulation shows that the theory predicts a too strong non-monotonous dependence of the recoil distance on the applied force.

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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