Direct Measurement of Unsteady Microscale Stokes Flow Using Optically Driven Microspheres
Direct Measurement of Unsteady Microscale Stokes Flow Using Optically Driven Microspheres
复制标题
使用光驱动微球直接测量非稳态微尺度斯托克斯流
DOI：
10.1101/2020.10.28.354738
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Bruot N
中科院分区：
文献类型：
--
作者：
Bruot N
越来越多的真核生物鞭毛的动力学研究指出，它们的振荡频率足够高，以至于不稳定斯托克斯流的粘性渗透深度与鞭毛同步的尺度相当。将这些效应应用到同步理论中，需要了解振荡体周围的全局非定常流。然而，一直没有精确的实验测试的微观尺度上的最基本的方面，这种不稳定的斯托克斯流：被动示踪剂的轨道和位置依赖的相位滞后之间的振荡响应的流体在一个遥远的点和驱动粒子。在这里，我们报告的第一个这样的直接拉格朗日测量的非定常流。该方法使用30个亚微米示踪剂粒子的阵列，通过分时光阱定位在相对于较大的中心粒子的距离和角位置的范围内，然后通过振荡光阱以高达400 Hz的频率驱动。在这种微尺度范围内，由于对粒子运动的惯性影响和对斯托克斯阻力定律的有限频率修正都很小，示踪剂动力学被大大简化。示踪剂被发现显示椭圆Lissajous数字，其方向和几何形状是在协议的低频扩展的基础动力学，和实验相移之间的运动平行和正交的振荡轴表现出预测的缩放形式的距离和角度。同步动力学这些结果的可能影响进行了讨论。
A growing body of work on the dynamics of eukaryotic flagella has noted that their oscillation frequencies are sufficiently high that the viscous penetration depth of unsteady Stokes flow is comparable to the scales over which flagella synchronize. Incorporating these effects into theories of synchronization requires an understanding of the global unsteady flows around oscillating bodies. Yet, there has been no precise experimental test on the microscale of the most basic aspects of such unsteady Stokes flow: the orbits of passive tracers and the position-dependent phase lag between the oscillating response of the fluid at a distant point and that of the driving particle. Here, we report the first such direct Lagrangian measurement of this unsteady flow. The method uses an array of 30 submicron tracer particles positioned by a time-shared optical trap at a range of distances and angular positions with respect to a larger, central particle, which is then driven by an oscillating optical trap at frequencies up to 400 Hz. In this microscale regime, the tracer dynamics is considerably simplified by the smallness of both inertial effects on particle motion and finite-frequency corrections to the Stokes drag law. The tracers are found to display elliptical Lissajous figures whose orientation and geometry are in agreement with a low-frequency expansion of the underlying dynamics, and the experimental phase shift between motion parallel and orthogonal to the oscillation axis exhibits a predicted scaling form in distance and angle. Possible implications of these results for synchronization dynamics are discussed.
登录
查看更多内容
远距离交互
DOI：
--
发表时间：
2002
期刊：
影响因子：
--
作者：
D. Frenkel;B. Smit
通讯作者：
B. Smit
绿藻作为生物流体动力学的模型生物。
影响因子：
27.7
作者：
Goldstein RE
通讯作者：
Goldstein RE
影响因子：
5.5
作者：
Maestro, Armando;Bruot, Nicolas;Cicuta, Pietro
通讯作者：
Cicuta, Pietro
影响因子：
8.6
作者：
Kotar, Jurij;Debono, Luke;Cicuta, Pietro
通讯作者：
Cicuta, Pietro
零雷诺数近似对于纤毛流是否有效？
影响因子：
8.6
作者：
Da Wei;Parviz G. Dehnavi;Marie‐Eve Aubin‐Tam;D. Tam
通讯作者：
D. Tam