Traveling Waves and Defect-Initiated Turbulence in Electroconvecting Nematics

Abstract

A novel time-dependent state in the form of traveling waves in electrohydrodynamic convection in a thin (15 \ensuremath{\mu}m) cell of very large aspect ratio is experimentally studied. The transition leading to uniform waves is a continuous one bifurcating directly from the homogeneous state. The onset of spatiotemporal turbulence in this 2D system is characterized by the appearance of topological defects. The number of defects increases with the control parameter, and their statistical distribution is in very good quantitative agreement with a theoretical curve recently derived for "topological turbulence."