Simple shear and small amplitude oscillatory rectilinear shear permeation flows of cholesteric liquid crystals
Simple shear and small amplitude oscillatory rectilinear shear permeation flows of cholesteric liquid crystals
复制标题
胆甾型液晶的简单剪切和小振幅振荡直线剪切渗透流
DOI：
--
复制
发表时间：
2002
期刊：
影响因子：
--
通讯作者：
A. Rey
中科院分区：
文献类型：
--
作者：
A. Rey
制定了受到慢稳态简单剪切和低频小振幅振荡剪切流作用的棒状胆甾液晶模型，并将其应用于渗透流，也称为 Helfrich 渗透流 [Helfrich (1969, 1970)]，此时胆甾螺旋沿速度方向取向，并且取向扭曲保留了原始的平面手性结构。在渗透流中，弹力恰好平衡粘性力。小内部长度尺度（螺旋螺距）的存在导致在任何剪切速率和任何驱动频率下速度和方向场中的边界层行为。边界层区域的厚度为节距的量级。表观粘度比典型的向列粘度大一个与间隙厚度与节距长度之比成比例的系数。该效应是由于埃里克森弹性应力造成的。胆甾醇对小振幅振荡剪切的响应对应于纯粘性......
A model of rod-like cholesteric liquid crystals subjected to slow steady simple shear and low frequency small amplitude oscillatory shear flow is formulated and applied to permeation flow, also known as Helfrich permeation flow [Helfrich (1969, 1970)], when the cholesteric helix is oriented along the velocity direction and the orientation distortions retain the original planar chiral structure. In permeation flow the elastic forces exactly balance viscous forces. The presence of a small internal length scale (pitch of the helix) leads to boundary layer behavior in the velocity and orientation fields at any shear rate and at any driving frequency. The thickness of the boundary layer region is of the order of the pitch. The apparent viscosity is larger than typical nematic viscosities by a factor proportional to the ratio of the gap thickness to the pitch length. The effect is due to the Ericksen elastic stress. The response of cholesterics to small amplitude oscillatory shear corresponds to a purely viscou...