Qi Zhiyuan, Ferguson Kyle, Sechrest Yancey, Munsat Tobin, Park Cheol Soo, Glaser Matthew A, Maclennan Joseph E, Clark Noel A, Kuriabova Tatiana, Powers Thomas R
Department of Physics, University of Colorado, Boulder, Colorado 80309, USA.
Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA.
Phys Rev E. 2017 Feb;95(2-1):022702. doi: 10.1103/PhysRevE.95.022702. Epub 2017 Feb 22.
Thin fluid membranes embedded in a bulk fluid of different viscosity are of fundamental interest as experimental realizations of quasi-two-dimensional fluids and as models of biological membranes. We have probed the hydrodynamics of thin fluid membranes by active microrheology using small tracer particles to observe the highly anisotropic flow fields generated around a rigid oscillating post inserted into a freely suspended smectic liquid crystal film that is surrounded by air. In general, at distances more than a few Saffman lengths from the meniscus around the post, the measured velocities are larger than the flow computed by modeling a moving disklike inclusion of finite extent by superposing Levine-MacKintosh response functions for pointlike inclusions in a viscous membrane. The observed discrepancy is attributed to additional coupling of the film with the air below the film that is displaced directly by the shaft of the moving post.
嵌入在具有不同粘度的大量流体中的薄流体膜，作为准二维流体的实验实现以及生物膜的模型，具有根本的研究意义。我们通过主动微流变学，利用小示踪粒子来探测薄流体膜的流体动力学，以观察围绕插入自由悬浮的近晶液晶膜（该膜被空气包围）中的刚性振荡柱体所产生的高度各向异性的流场。一般来说，在距离柱体周围弯月面几个萨夫曼长度以上的距离处，测量到的速度大于通过叠加粘性膜中点状包含物的莱文 - 麦金托什响应函数来模拟有限范围的移动盘状包含物所计算出的流速。观察到的差异归因于膜与膜下方空气的额外耦合，膜下方的空气被移动柱体的轴直接排开。
