PATTERN FORMATION AND SYMMETRY OF FIELDS IN ELECTROHYDRODYNAMICSS IN LIQUID CRYSTALS

液晶电化学场的图案形成和对称性

基本信息

批准号：
08454107
负责人：
KAI Shoichi
金额：
$ 5.06万
依托单位：
KYUHSU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

The electrohydrodynamic instability (EHD) in nematic liquid crystals is investgated using homeotropically aligned systems where the nematic director orients perpendicular to the electrodes. In homeotropically aligned EHD the system has a continuously rotational symmetry as well as a translational one. This symmetry leads to additional new Goldstone modes at onset of convections and dramatically changes the bifurcation properties as well as observed patterns. The obtained results in the present study are as follows.1) In the system with additional Goldstone modes due to continuous rotational symmetry, a direct transition from nonconvective states to spatiotemporal chaos is observed.2) The bifuration at onset occurs supercritically. The correlation time of macroscopic randam motions becomes longer inversely proportional to the deviation from the onset, that is, a critical slowing down phenomenon is observed. From this behavior the spatiotemporal chaos has been named the soft mode turbule … More nce (SMT) .3) The stability of additional Goldstone modes can be controlled by application of magnetic field since magnetic fields induce the prefered axis and suppress the generation of the Goldstone modes. Therefore under superimposing strong magnetic fields periodic patterns are observed.4) New type of zig-zag patterns are found out which are not predicted in currently available thcories.5) It is clarified from these findings that driving forccs which result in SMT are induced by non-parallel orientation between the director and the wavevector of covective rolls.6) Depending on the strength of magnetic fields there are two types of spatiotemporal chaos. The transition between them is clearly defined by looking the spatial power spectra of patterns and distribution functions of roll orientations.7) The rolls exist either in all directions or only in the prefered directions induced by magnetic fields. Then the formet one is called SMT and the latter the defect turbulence.Thus excess of symmetry can result in chaos and the intrinsic mechanism for direct transition to chaos from a spatially uniform state is destabilization of short-wavelength modes due to coupling with Goldstone modes of the spectrum. Based on these results, new theory will be expected in EHD. Less

列在列液晶中的电水动力不稳定性（EHD）是使用同型对齐系统进行投资的，在该系统中，nematory nematory temart in垂直于电极。在同型对齐的EHD中，该系统具有连续的旋转对称性以及转换的对称性。这种对称性在开始时会导致其他新的金石模式，并极大地改变了分叉特性以及观察到的模式。在本研究中获得的结果如下。1）在系统中，由于连续的旋转对称性，在系统中具有其他金石模式，从非概念性状态直接过渡到空间颞叶。宏观Randam动作的相关时间与偏离发病的偏移相反，也就是说，观察到一个关键的减慢现象。从这种行为中，空间暂时的混乱已被命名为软模式湍流……更多的NCE（SMT）.3）可以通过应用磁场来控制其他金矿模式的稳定性，因为磁场诱导了首选轴并抑制了金石模式的产生。因此，在叠加强磁场下观察到周期性模式。它们之间的过渡是通过观察图案的空间功率光谱和滚动方向的分布函数来明确定义的。7）卷卷在各个方向或仅在磁场引起的首选方向上存在。然后，Formet One称为SMT，后者称为缺陷湍流。超过对称性的可能导致混乱和直接从空间均匀状态过渡到混乱的固有机制，这是由于与光谱的金石模式耦合而破坏了短波长模式。基于这些结果，EHD将期望新理论。较少的