Shear-induced undulation of smectic-$\mathsf{A}$: Molecular dynamics simulations vs. analytical theory

Experiments on a variety of systems have shown that layered liquids are unstable under shear even if the liquid layers are planes of constant velocity. We investigate the stability of smectic-A like liquids under shear using Molecular Dynamics simulations and a macroscopic hydrodynamic theory (including the layer normal and the director as independent variables). Both methods show an instability of the layers, which sets in above a critical shear rate. We find a remarkable qualitative and reasonable quantitative agreement between both methods for the spatial homogeneous state and the onset of the instability.Received: 2 October 2003, Published online: 9 March 2004PACS: 61.30.Dk Continuum models and theories of liquid crystal structure - 61.25.Hq Macromolecular and polymer solutions; polymer melts; swelling - 05.70.Ln Nonequilibrium and irreversible thermodynamics - 83.10.Rs Computer simulation of molecular and particle dynamics - 83.50.Ax Steady shear flows, viscometric flowTh.Soddemann : Present address: Rechenzentrum der Max-Planck-Gesellschaft, Boltzmannstrasse 2, 85748 Garching, Germany