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DY: Fachverband Dynamik und Statistische Physik
DY 9: Nonlinear dynamics, synchronization and chaos I
DY 9.6: Vortrag
Montag, 25. Februar 2008, 18:15–18:30, MA 004
Relaxation oscillations and chaos in the torsional Quincke pendulum — •Michael Zaks1 and Mark Shliomis2 — 1Institut für Physik, Humboldt-Universität zu Berlin — 2Ben-Gurion University, Beer Sheva, Israel
Let a constant electric field act upon an insulating body suspended into a liquid with low conductivity. If the field is sufficiently strong, the body starts to rotate; this phenomenon is known under the name of Quincke effect. Dynamics of this torsional motion has been recently shown to obey the Lorenz equations, provided the elasticity of suspension is discarded: depending on the field strength, the Quincke rotor exhibits stationary and chaotic rotations. We take elasticity into account and demonstrate that in a certain range of the field intensity the rotor should perform relaxational oscillations with large amplitude. Explicit expressions relate the amplitude and period of oscillations to physical parameters of the problem: intensity of the field, viscosity of the liquid and elasticity of the suspension. In stronger fields the regime of large-scale relaxational oscillations breaks down abruptly and is replaced by minor erratic fluctuations of the pendulum. We explain this transition in terms of the global bifurcations in the Lorenz equations.