Propulsion of an elastic filament in a shear-thinning fluid
Propulsion of an elastic filament in a shear-thinning fluid
复制标题
剪切稀化流体中弹性丝的推进
DOI：
10.1039/d0sm02130j
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发表时间：
2021
期刊：
影响因子：
3.4
通讯作者：
Pak, On Shun
中科院分区：
文献类型：
--
作者：
Qin, Ke;Peng, Zhiwei;Chen, Ye;Nganguia, Herve;Zhu, Lailai;Pak, On Shun
一些微生物和人造微型游泳者通过其柔性附肢与周围液体的相互作用以低雷诺数 (Re) 推进。虽然它们的运动已经用牛顿流体假设进行了广泛的研究，但在现实的生物环境中，这些微型游泳者总是会遇到流变复杂的流体。特别是，许多生物液体（例如血液和不同类型的粘液）具有剪切稀化粘度。这种普遍存在的非牛顿流变学对灵活游泳者表现的影响在很大程度上仍然未知。在这里，我们提出了第一项研究，以检验剪切稀化流变学如何改变流体-结构相互作用，从而改变弹性游泳器在低 Re 下的推进性能。通过磁驱动的简单弹性游泳器，我们证明剪切稀化流变学可以增强或阻碍弹流体动力推进力，具体取决于弹性力和粘性力以及磁驱动之间复杂的相互作用。我们还使用降阶模型来阐明在不同物理状态下观察到的增强和受阻推进力的机制。这些结果和加深的理解可以指导非牛顿流体中柔性微型游泳器的设计。
Some micro-organisms and artificial micro-swimmers propel at low Reynolds numbers (Re) via the interaction of their flexible appendages with the surrounding fluid. While their locomotion has been extensively studied with a Newtonian fluid assumption, in realistic biological environments these micro-swimmers invariably encounter rheologically complex fluids. In particular, many biological fluids such as blood and different types of mucus have shear-thinning viscosities. The influence of this ubiquitous non-Newtonian rheology on the performance of flexible swimmers remains largely unknown. Here, we present a first study to examine how shear-thinning rheology alters the fluid-structure interaction and hence the propulsion performance of elastic swimmers at low Re. Via a simple elastic swimmer actuated magnetically, we demonstrate that shear-thinning rheology can either enhance or hinder elastohydrodynamic propulsion, depending on the intricate interplay between elastic and viscous forces as well as the magnetic actuation. We also use a reduced-order model to elucidate the mechanisms underlying the enhanced and hindered propulsion observed in different physical regimes. These results and improved understanding could guide the design of flexible micro-swimmers in non-Newtonian fluids.