AA_CSU  AA_CSU  AA_CSU 


RESEARCH  ON ELECTROCONVECTION IN NEMATIC LIQUID CRYSTALS*

NSF Funded Collaborative Research:

Pattern Formation and Dynamics in Electroconvection of Nematic Liquid Crystals -
A Theoretical and Experimental Study of the Weak Electrolyte Model;
PIs:  Iuliana Oprea, Gerhard Dangelmayr; Colorado State University,  Jim Gleeson, Kent State University
PhD Grad Students: Josh Ladd, CSU, Gyanu Acharia, KSU

Note: picture and other files to come soon

    The wide range of applications of liquid-crystalline materials has created new areas of academic research and raised the interest of specialists in nonlinear dynamics and pattern formation. The overhelming preponderence of the multi-billion dollar global market for liquid crystal infromation displays continues to be dominated by technologies based on nematics. Our research applies inovative analytical and computational techniques to elucidate the complex mechanism of pattern formation in the electroconvection of nematic liquid crystals, an important model system for understanding pattern formation in nature.  Although our research focusses specifically on electroconvection, the mathematical methods developed in this project should be applicable to a variety of systems, in particular if anisotropy becomes important.

    The work done represents an unique and novel interdisciplinary research that allows us to go from experiments to the complex mathematical model of the physical system and backwards in a highly nontrivial extended system far from equilibrium.  We developed the mathematical tools  and model that allow us to compare the experimental data with our calculated data, and use our model for the determination of important but unknown physical model parameters, in order to predict the behavior of the system and guide new experiments at KSU.  The link below describes some of the experiemtal results obtained by Jim Gleeson and his group:

DEPENDENCE OF ROLL FREQUENCY ON DRIVING  FREQUENCY IN NEMATIC LIQUID CRYSTAL MIXTURE, G. Acharia, J. Gleeson 2005

A picture of the whole research team in the Physics Lab, in KSU, Kent, OH;
from left to right: Gerhard Dangekmayr, Jim Gleeson, Iuliana Oprea and
the students Gyanu Acharia and Josh Ladd:
 

    The main objective of our research is the investigation and characterization of complex patterns, including the spatio-temporal chaos, observed experimentally and numerically in the nematic electroconvection. Our research is based on the mathematical and experimental analysy of the weak electrolyte model for the nematic electroconvection.  Here you will find a short description of the mathematical aspects  of the weak electrolyte model:



- link .pps presentation -


    Spatiotemporal chaos is a deterministic pattern with unpredictable spatial and temporal variation, that occurs in a wide variety of systems including lasers, thermal convection, nematic electroconvection, chemical reaction systems, population dynamics, snow dynamics and so on. The understanding, characterization and control of STC are a major challenge in nonlinear dynamics. Studying spatio-temporal chaos in nematic electroconvection, a paradigm model for pattern formation an dynamics in anisotropic syatems, will have an important impact in understanding these systems.

    We  have developed a series of mathematical techniques, together with the corresponding software, to investigate complexe patterns, including STC, observed by our colleagues at KSU in their experiments or found by us in the numerical simulation of the partial differential equations for the amplitudes of the patterns at the onset. We illustrate below some of our findings and activities.


Result of a KL analsis of the experimental spatiotemporal chaos



*) This material is based upon work supported by the National Science Foundation under Grant No. 0407418. Any oppinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of NSF.

more on Pattern Formation in Dissipative Systems:
DYNAMICS and BIFURCATIONS of PATTERNS in DISSIPATIVE SYSTEMS
           NSF-CSU Workshop, 19-22 May 2003, Ft. Collins, CO