Nonequilibrium fluctuations from a nematic under a thermal gradient and a gravity field*
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  • 作者:Jorge F. Camacho ; Rosalío F. Rodríguez
  • 关键词:Statistical and Nonlinear Physics
  • 刊名:The European Physical Journal B
  • 出版年:2017
  • 出版时间:February 2017
  • 年:2017
  • 卷:90
  • 期:2
  • 全文大小:
  • 刊物类别:Physics and Astronomy
  • 刊物主题:Condensed Matter Physics; Physics, general; Complex Systems; Fluid- and Aerodynamics; Solid State Physics;
  • 出版者:Springer Berlin Heidelberg
  • ISSN:1434-6036
  • 卷排序:90
文摘
The fluctuating hydrodynamic treatment developed in the previous article for a nematic liquid crystal under the influence of a thermal gradient α and a uniform gravity field g, is used to calculate its Rayleigh light scattering spectrum. We find that the dissipative thermal gradient force enhances the Rayleigh-line intensity which varies as k-4 with the fluctuations of the wave number k. The Rayleigh line consists of three central Lorentzians, two of which are determined by the visco-heat modes coupling the entropy and director fluctuations, which is a pure non-equilibrium effect. The third Lorentzian is due only to director fluctuations. We find that the former peaks contain the Rayleigh wings owing to the orientational fluctuations of the aniosotropic molecules. It is also shown that the obtained spectrum reduces to the known equilibrium spectrum of a nematic and to that of a simple fluid. For the particular case in which the decay rates are diffusive, we calculate and plot the amplitudes of non-equilibrium fluctuations of the dynamic structure factor as a function of |α|2/k4, and also, the intermediate function in the equilibrium and non-equilibrium states.

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