Inhibited pattern formation by asymmetrical high voltage excitation in nematic fluids

TL;DR

This study investigates how asymmetrical high voltage excitation in nematic liquids inhibits electroconvection pattern formation, extending the patternless region beyond individual voltage thresholds, challenging existing theories.

Contribution

It provides experimental evidence that superposed ac and dc voltages can suppress pattern formation in nematic fluids, contrary to standard electroconvection theory.

Findings

Superposed ac and dc voltages inhibit pattern formation.

Patternless region extends beyond individual voltage thresholds.

Qualitative explanation for conductive EC, challenge for dielectric EC.

Abstract

In contrast to the predictions of the standard theory of electroconvection (EC), our experiments showed that the action of superposed ac and dc voltages rather inhibits pattern formation than favours the emergence of instabilities; the patternless region may extend to much higher voltages than the individual ac or dc thresholds. The pattern formation induced by such asymmetrical voltage was explored in a nematic liquid crystal in a wide frequency range. The findings could be qualitatively explained for the conductive EC, but represent a challenging problem for the dielectric EC.