Multifrequency Driven Nematics

Convection driven by centrifugal buoyancy in nematics

The onset of thermal convection in a nematic contained in a vertical rotating cylindrical annulus heated from the outside is studied as a function of the planar alignment of the liquid crystal director n. When n is horizontal, the results confirm data on gravitational buoyancy. An original first order like convection mode is obtained when n is parallel to the cylinder axis. Thermal convection i...

Overdamped Deterministic Ratchets Driven by Multifrequency Forces∗

We investigate a dissipative, deterministic ratchet model in the overdamped regime driven by a rectangular force. Extensive numerical calculations are presented in a diagram depicting the drift velocity as a function of a wide range of the driving parameter values. We also present some theoretical considerations which explain some features of the mentioned diagram. In particular, we proof the e...

On-off Intermittency in Stochastically Driven Electrohydrodynamic Convection in Nematics

On-o Intermittency in Stochastically Driven Electrohydrodynamic Convection in Nematics

We report on-oo intermittency in electroconvection of nematic liquid crystals driven by a dichotomous stochastic electric voltage. With increasing voltage amplitude we observe short bursts of spatially regular stripe patterns which interrupt laminar phases of undistorted director state. Near a critical value of the amplitude the distribution of the duration of laminar phases is governed over se...

On electrically driven pattern-forming instabilities in planar nematics

2014 The theoretical description of the threshold and near-threshold behavior of electrohydrodynamic convection in nematic liquid crystals in the (low-frequency) conduction regime is reconsidered. We present essentially the full three-dimensional linear stability analysis of the basic state and a major part of the weaklynonlinear theory of the convective state. Boundary conditions at the upper ...