Convection instabilities in nematic liquid crystals
Convection instabilities in nematic liquid crystals
复制标题
向列液晶中的对流不稳定性
DOI：
10.1146/annurev.fl.27.010195.002503
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发表时间：
1995
影响因子：
27.7
通讯作者：
W. Pesch
中科院分区：
文献类型：
--
作者：
L. Kramer;W. Pesch
在过去的几十年里，人们对水动力不稳定性中的模式形成进行了深入的研究（Manneville 1990, Cross & Hohenberg 1993）。简单流体中的瑞利-贝纳德对流（RBC）就是最好的例子。在这篇综述中，我们的目标是引起人们对向列相液晶（lc）中发现的丰富多样的场景的关注。液晶是由高度各向异性的有机分子组成的材料，其相反映了这种各向异性。向列型LCs（向列型）是完全液态的，没有远距离平移，但具有分子的远距离单轴定向有序。因此，在公认的流体力学描述中（Ericksen 1976, Leslie 1979, de Gennes 1974, Stephen & Straley 1974, Chandrasekhar 1977），表征首选轴的方向必须作为附加变量包括在内。那么一个有6个剪切粘度lXI'•。•、动量平衡方程（广义Navier-Stokes方程）中的1X6与1X6 -1X5 = 1X3 + IXz （1X4/2对应各向同性粘度）。在导向方程中，可以松散地与扭矩平衡联系起来，其中有两个旋转粘度YI和Yz，它们可以用剪切粘度来表示。对于这里所讨论的低分子量材料，下列各项有关的粘度为10-1 kg m -1 s -1数量级。需要三个方向弹性模块，kl), k22‘ k33’来描述三个基本的
Pattern formation in hydrodynamic instabilities has been studied intensely over the past few decades (Manneville 1990, Cross & Hohenberg 1993). Rayleigh-Benard convection (RBC) in simple fluids has been the prime example. Our goal in this review is to draw attention to the rich variety of scenarios found in nematic liquid crystals (LCs). Liquid crystals are materials made up of highly anisotropic organic molecules in a phase that reflects this anisotropy. The class of nematic LCs (nematics) is fully liquid without long-range translational, but with long-range uniaxial orienta tiona I ordering of the molecules. Thus in the well-established hydrodynamic description (Ericksen 1 976, Leslie 1 979, de Gennes 1974, Stephen & Straley 1974, Chandrasekhar 1977) the director n characterizing the preferred axis has to be included as an additional variable. One then has six shear viscosities lXI' • . • , 1X6 with 1X6 -1X5 = 1X3 + IXz (1X4/2 corresponds to the isotropic viscosity) in the momentum balance equation (generalized Navier-Stokes equation). In the director equation, which can be associated loosely with a balance of torque, there are two rotational viscosities, YI and Yz, which are expressible in terms of the shear viscosities. For the low-molecular-weight materials discussed here the vis cosities relevant in the following are of order 10-1 kg m -I S-I. One needs three orientational elastic modules, kl), k22' k33' to describe the three basic