Flagellar swimming in viscoelastic fluids: role of fluid elastic stress revealed by simulations based on experimental data
Flagellar swimming in viscoelastic fluids: role of fluid elastic stress revealed by simulations based on experimental data
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DOI：
10.1098/rsif.2017.0289
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发表时间：
2017-10
影响因子：
3.9
通讯作者：
Chuanbin Li;Boyang Qin;A. Gopinath;P. Arratia;B. Thomases;R. Guy
中科院分区：
文献类型：
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作者：
Chuanbin Li;Boyang Qin;A. Gopinath;P. Arratia;B. Thomases;R. Guy
许多重要的生物功能取决于微生物在粘弹性流体如粘液和湿土壤中的运动能力。流体弹性对运动性的影响仍然知之甚少，部分原因是游泳者的划水取决于流体介质的性质，这混淆了观察到的行为变化的机制。在这项研究中，我们使用的实验数据的牛顿和粘弹性流体的莱茵衣藻游泳的步态作为输入的数值模拟，解耦游泳者的步态和流体类型，以隔离流体弹性对游泳的影响。在粘弹性流体中，采用牛顿步态的细胞游得更快，但产生更大的应力并使用更多的功率，因此粘弹性步态更有效。此外，我们表明，基于粘性流体理论的游泳的基本原则错过了重要的流体动力学：流体弹性提供了一种弹性记忆效应，增加了向前和向后的速度，和（不像纯粹的粘性流体）更大的流体应力聚集在鞭毛运动切线的游泳方向，与正常方向相比。
Many important biological functions depend on microorganisms' ability to move in viscoelastic fluids such as mucus and wet soil. The effects of fluid elasticity on motility remain poorly understood, partly because the swimmer strokes depend on the properties of the fluid medium, which obfuscates the mechanisms responsible for observed behavioural changes. In this study, we use experimental data on the gaits of Chlamydomonas reinhardtii swimming in Newtonian and viscoelastic fluids as inputs to numerical simulations that decouple the swimmer gait and fluid type in order to isolate the effect of fluid elasticity on swimming. In viscoelastic fluids, cells employing the Newtonian gait swim faster but generate larger stresses and use more power, and as a result the viscoelastic gait is more efficient. Furthermore, we show that fundamental principles of swimming based on viscous fluid theory miss important flow dynamics: fluid elasticity provides an elastic memory effect that increases both the forward and backward speeds, and (unlike purely viscous fluids) larger fluid stress accumulates around flagella moving tangent to the swimming direction, compared with the normal direction.