Department of Physics, Kyoto University, Kyoto 606-8502, Japan.
Phys Rev Lett. 2012 Dec 21;109(25):257801. doi: 10.1103/PhysRevLett.109.257801. Epub 2012 Dec 20.
When a nematic liquid crystal is confined in a porous medium with strong anchoring conditions, topological defects, called disclinations, are stably formed with numerous possible configurations. Since the energy barriers between them are large enough, the system shows multistability. Our lattice Boltzmann simulations demonstrate dynamic couplings between the multistable defect pattern and the flow in a regular porous matrix. At sufficiently low flow speed, the topological defects are pinned at the quiescent positions. As the flow speed is increased, the defects show cyclic motions and nonlinear rheological properties, which depend on whether or not they are topologically constrained in the porous networks. In addition, we discover that the defect pattern can be controlled by controlling the flow. Thus, the flow path is recorded in the porous channels owing to the multistability of the defect patterns.
当向列液晶被限制在具有强锚定条件的多孔介质中时，会形成拓扑缺陷，称为位错，它们具有多种可能的构型。由于它们之间的能垒足够大，因此系统表现出多稳态。我们的晶格玻尔兹曼模拟演示了多稳态缺陷模式与规则多孔基质中流动之间的动态耦合。在足够低的流速下，拓扑缺陷被固定在静止位置。随着流速的增加，缺陷会表现出循环运动和非线性流变特性，这取决于它们在多孔网络中是否受到拓扑约束。此外，我们发现可以通过控制流来控制缺陷模式。因此，由于缺陷模式的多稳态性，可以在多孔通道中记录流动路径。
