2005, Vol.8, No.3, pp.274-280

Hydrodynamic fluctuations of a horizontal layer of anisotropic liquid heated from below were considered in the vicinity of bifurcation point in [1]. It is a famous fact that in that region convection sets in because of buoyancy. Anisotropic liquid in problem under consideration may be described with the aid of a unit vector which represents averaged direction of long axes of molecules. We deal with liquids which consist of organic molecules and have the so-called planar orientation, i.e. molecules have the direction, parallel to the confining plates and coinciding with OX axis. One of the mentioned kinds of liquids is the liquid crystal. Variety of liquid crystals: nematic, cholesteric and smectic give rise of the set of dissipative structures. Increasing interest in anisotropic liquid may be related with considerable advance in our knowledge of a rich variety of novel effects associated with liquid crystals. Such progress has been largely due to the availability of a viable macroscopic theory and the motivation of technological applications. As it was mentioned above the classical Rayleigh-Benard problem is that in which a sample of Newtonian fluid contained between two large horizontal flat plates is subjected to an adverse thermal gradient. Provided the temperature difference between the plates is less than some critical value, the physical system remains in equilibrium (but not thermal one) and there is no flow. However, as this critical value is exceeded the onset of stationary convection is observed. And this simple hydrodynamic instability occurs when the buoyancy force due to thermal expansion near the lower plate is sufficient to overcome the opposing viscous shear force. As a result threshold values for stationary convection are drastically reduced and instability can occur when heating is from above as well as below. In addition, oscillatory convective instabilities with inverse bifurcation and hysteresis effects are possible.
Key words: anisotropic liquid, nematic liquid crystal, correlation function, functional, thermal gradient

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