权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Pattern Formation in Nonequilibrium Dissipative Systems-Dynamics of Dissipative Structures in Liquid Crystals

非平衡耗散系统中的图案形成-液晶耗散结构动力学

基本信息

批准号：
10440117
负责人：
KAI Shoichi
金额：
$ 8.58万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

The aim of this research project is to understand a role of system symmetries on pattern formations in nonequilibrium dissipative systems such as electrohydrodynamic instability (EHD) in nematic liquid crysals. In the EHD system, there are two different alignments ; planar and homeotropic ones. Regarding pattern formations in planar systems various new results have been obtained. Contrary to this, the study of EHD in homeotropic systems was very few, and no interesting results and no new physics were obtained so far. In the present study, we especially pay our attention to symmetries of the systems. Pattern formations in EHD strongly depend on the initial synmmetries of the systems, that is either on planar or homeotropic alignments. However the so-called chevron patterns appear independently of initial align-ments, i.e. initial symmetry of the system. Therefore we investigate at first the formation mechanism of this type of patterns. Then it is found that the chevron patterns are clas … More sified into four different types, chevron A and B, both of which are further classified into the patterns with periodic defect orientation(DMC) and defect free chevrons (DFC). DMC forms due to competitive instability between defect formation and director defomation similar to Turing instability. The mechanism of DFC in chevron A and B are unknown yet. It becomes however clear that the chevron patterns are fomed independently of boundary anchoring which always leads to no symmetry dependence in the pattern formation.Regarding EHD in a homeotropic alignment with a continuously rotational symmetry, a spatio-temporal chaos called the softmode turbulence (SMT) appears. SMT is a unique turbulence in a weakly nonlinear regime continuously connecting to a uniform stationary state via a single supercritical bifuraction and therefore expected to be understood precisely. This results from the additional Goldstone mode due to the continuously rotational symmetry, which can be suppressed by application of magnetic fields. The phase diagram has been obtained on a plane among the parameters of applied electric field intensity, its frequency and magnetic field strength. Two different STC's have been found out which depend on the symmetry of the system. Thus the small change of alignments (symmetries) leads to the big difference of pattern formations. The formation dynamics must be classified into two categories ; universal dynamics independent of symmetries and individual dynamics dependent on symmetries. Less

本研究项目的目的是了解系统对称性在非平衡耗散系统（如向列液晶中的电流体动力不稳定性（EHD））中的模式形成中的作用。在EHD系统中，有两种不同的路线；平面的和各向同性的。关于平面体系的图案形成，获得了许多新的结果。与此相反，在同向异性体系中对EHD的研究很少，迄今为止也没有得到有趣的结果和新的物理现象。在目前的研究中，我们特别关注系统的对称性。EHD中的模式形成强烈依赖于系统的初始对称性，即平面或各向同性排列。然而，所谓的纹样是独立于初始排列，即系统的初始对称性而出现的。因此，我们首先研究了这类图案的形成机制。进一步将其划分为A型和B型四种不同类型，并将其进一步划分为周期性缺陷取向型（DMC）和无缺陷型（DFC）。DMC的形成是由于缺陷形成和导向器变形之间的竞争不稳定，类似于图灵不稳定。DFC在纹样A和纹样B中的作用机制尚不清楚。然而，很明显，纹样是独立于边界锚定而形成的，边界锚定总是导致纹样形成中没有对称依赖。在连续旋转对称的各向同性排列中，会出现一种称为软模湍流（SMT）的时空混沌。SMT是一种独特的弱非线性湍流，通过单个超临界分岔连续连接到均匀定态，因此有望被精确地理解。这是由于连续旋转对称导致的额外的戈德斯通模式，可以通过施加磁场来抑制。在外加电场强度、频率和磁场强度参数的平面上得到了相图。已经发现了两种不同的STC，它们依赖于系统的对称性。因此，排列（对称）的微小变化导致了图案形成的巨大差异。地层动力学必须分为两类；独立于对称性的普遍动力学和依赖于对称性的个体动力学。少