Turbulence and Stochastic Processes in Nematic Liquid Crystals

Abstract

In this work we studied the electrohydrodynamics instabilities (EHD) from a different point of view. We used the traditional tools, belonging to the traditional fluid turbulence framework, to the world of liquid crystals. This tools in addition, for the first time, a 3D scanning of the NLC sample driven in these turbulent regimes, give us some interesting results. As an example a fragmentation of the large scale structures (Williams Domains) whit characteristics similar to the Richardson cascade. We also studied, for the first time, the intensity fluctuation at different depth z inside the sample, and we found a strong non gaussianity in the probability density function of this fluctuation. Further information has been obtained by by studying the decorrelation processes in EHD. We found a local transition between two different regimes: the classical Kolomokorov K41 law in the y direction, and a random sweeping decorrelation in the opposite x direction. Finally we study the weak localization of light obtained during the EHD. We found a drastic reduction in the scattering mean free path `? and a strong enhancement of the backscattering cone.