HYDRODYNAMICS OF SMECTIC-C LIQUID-CRYSTALS - FIELD AND FLOW-INDUCED INSTABILITIES IN CONFINED GEOMETRIES

Following the Ericksen-Leslie approach, we formulate a complete nonlin ear macroscopic theory of the isothermal hydrodynamics of smectic-C li quid crystals. We assume an asymmetric stress tensor and incorporate t he essential features of a hydrodynamic theory of a smectic phase, i.e ., permeation and variations in layer spacing. Using Onsager's recipro city relations, we find that entropy production is described by 16 vis cosity coefficients and a permeation constant associated with the diss ipative dynamics of the layered system. We study the reorientation dyn amics of the c vector under the destabilizing influence of an external field. We stress that permeation is important and that transverse flo ws along and normal to the layers exist. We have also studied certain instabilities that can arise in shear hows. As a consequence of permea tion, in Poiseuille flow with the layers parallel to the plates, we fi nd that the length of the inlet section can be very large being many t imes the lateral dimension. When the layers are perpendicular to the p lates, an analog of the nematic Hall effect is shown to exist even in the absence of an aligning external field.