Experimentally shown that the shear flow of a ferroelectric smectic C* liquid crystal (FLC) in flat capillary with homeotropic boundary conditions can be described in the framework of the Newtonian fluids theory if the pitch p 0 of the FLC helix is much less than the capillary gap. The motion of the contact line during the filling of the capillary was recorded in the experiment and compared with the theory, which made it possible to estimate the shear viscosity coefficient η  0.5 Pas, which turned out to be much larger than the rotational viscosity coefficient  . In the capillary filling process, the principal optical axis of the FLC helical structure was oriented mainly perpendicular to the substrates, and the smectic layers were parallel to the substrates. At the same time, narrow dislocation bands arose along the flow direction. The principal optical axis deviated from the normal to the substrates at different angles within the dislocation bands. The total area occupied by dislocations does not exceed 5 % of the flow area; therefore, dislocations do not have a significant effect on the rheological behavior of the smectic C* phase.

In this paper we describe the first experimental realization of the previously proposed optofluidic liquid crystal device based on electro-osmotic flows arising in the porous polymer (PET) film filled with a nematic liquid crystal (NLC). These flows induced Poiseuille's shear flow of NLC through the plane channels with a hometropic orientation, which resulted in the flow induced modulation of the intensity of light, passed through the channels. The additional application of magnetic field provided the stabilization of the homeotropic orientation. The results of numerical calculations of hydrodynamic and optical characteristics of the device were compared with the experimental data.

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The results of experimental investigation of rheological properties of a nematic liquid crystal (NLC) 5CB (4cyano-4'-pentylbiphenyl) confined to submicron pores of polymer PET-films in the presence of AC electric field are presented. The decay flow method, elaborated previously for plane channels, was successfully adopted and applied to the LC-PET composite media, which can be considered as a number of cylindrical channels, connected in parallel schema, filled with flowing LC. It provides the calculation of the effective shear viscosity as a function of the electric field strength. The character of this function indicates on the electrically induced orientation transformation in LC inside pores due to breaking of a surface anchoring.

In this paper we report the new experimental results on the rise of a liquid crystal in flat capillaries with inner photosensitive surfaces. The capillaries with different surface orientations were prepared by the use of the photo-alignment technique. Such a surface treatment makes it possible to eliminate the noncontrollable influence of a nanorelief on the wetting process, which takes place in the rubbing treatment technique previously used in similar experiments. The dynamics of the capillary rise of a nematic liquid crystal 5CB (4-cyano-4′-pentylbiphenyl) in vertical plane capillaries with photo-aligned substrates were studied for the first time. It was found that the stationary value of a contact angle weakly depends on the direction of a planar surface orientation relative to the direction of a capillary rise. It has been shown that the application of strong electric fields resulted in a decreasing of the contact angle. The results, obtained for the nematic liquid crystal, are compared with the results of an investigation of the capillary flow in a shock-free ferroelectric smectic phase.