Berlin 2005 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 11: Nonlinear Dynamics
DY 11.6: Vortrag
Freitag, 4. März 2005, 11:45–12:00, TU H2032
Stimulation of subharmonic dynamics in electroconvection patterns — •Jana Heuer1, Thomas John2, and Ralf Stannarius1 — 1Otto-von-Guericke-Universität Magdeburg — 2Carl-von-Ossietzky-Universität Oldenburg
Electroconvection (EHC) in nematic liquid crystals is classically driven by periodic sine or square wave voltages. The spontaneous formation of regular patterns is a critical phenomenon and characterized by threshold values for the excitation field.
An important aspect of our investigations is the fundamental influence of the excitation wave form on the dynamic response of the observed dissipative system. We study how the generation of the newly discovered subharmonic pattern regime (first described in [1]) depends on the symmetry of the excitation. Therefore we analyze the spatio-temporal dynamics of the system near the threshold voltage experimentally.
Since electroconvection in nematics can be described by a system of two coupled ordinary differential equations, we compare these experimental results with theoretical calculations. Many other dynamic systems can be characterized by these simple ODEs, thus we try to derive general conclusions about the relationship between the symmetry of the excitation and the dynamic response of the system.
Furthermore we characterize higher instabilities that occur far from threshold compared to the higher instabilies in the classical regimes.
A comprehensive representation of the subharmonic regime is the ambition of our investigations.
[1] T. John and R. Stannarius, Phys. Rev. E 70, 025202 (2004)