Otto-von-Guericke Universität Magdeburg, Institute for Experimental Physics, D-39016 Magdeburg, Germany.
Phys Rev Lett. 2011 Dec 23;107(26):268301. doi: 10.1103/PhysRevLett.107.268301. Epub 2011 Dec 22.
Smectic liquid crystals form freely-suspended, fluid films of highly uniform structure and thickness, making them ideal systems for studies of hydrodynamics in two dimensions. We have measured particle mobility and shear viscosity by direct observation of the gravitational drift of silica spheres and smectic islands included in these fluid membranes. In thick films, we observe a hydrodynamic regime dominated by lateral confinement effects, with the mobility of the inclusion determined predominantly by coupling of the fluid flow to the fixed boundaries of the film. In thin films, the mobility of inclusions is governed primarily by coupling of the fluid to the surrounding air, as predicted by Saffman-Delbrück theory.
向列相液晶形成自由悬浮的、具有高度均匀结构和厚度的流体膜，是研究二维流体动力学的理想体系。我们通过直接观察包含在这些流体膜中的二氧化硅球和向列相小岛的重力漂移，测量了粒子的迁移率和剪切黏度。在厚膜中，我们观察到一个主要由横向限制效应控制的流体动力学状态，其中包含物的迁移率主要取决于流体流动与膜的固定边界的耦合。在薄膜中，根据 Saffman-Delbrück 理论的预测，包含物的迁移率主要由流体与周围空气的耦合决定。
