Abstract
We investigate the effects of shear flow on the smectic phase of thermotropic and lyotropic liquid crystals. We show that shear flow transforms a smectic-A thermotropic liquid crystal into an orthorhombic solid by the suppression of undulation fluctuations. In contrast, the lyotropic phase exhibits, in addition, a very striking enhancement of short-wavelength concentration fluctuations—a phenomenon that is analogous to a well-known effect in polymer solutions. We demonstrate this result, using both hydrodynamic theory and a microscopic model based on the Helfrich theory of membranes. The dispersion relation of the concentration fluctuations is in qualitative agreement with recent experiments on the phase in shear flow.
- Received 16 August 1991
DOI:https://doi.org/10.1103/PhysRevA.45.994
©1992 American Physical Society