Berlin 2012 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

DY: Fachverband Dynamik und Statistische Physik

DY 3: Fluid dynamics I

DY 3.4: Vortrag

Montag, 26. März 2012, 10:45–11:00, MA 144

Faraday wave patterns under excitation with time reversed asymmetric periodic wave forms — •Thomas John, Dirk Pietschmann, and Ralf Stannarius — Institut für Experimentelle Physik, Fakultät für Naturwissenschaften, Universität Magdeburg, Universitätsplatz 2, D-39106 Magdeburg, Germany

A vertically shaken (periodically exited) Newtonian liquid layer, called Faraday experiment, is a paradigm for pattern forming systems. We investigate experimentally and numerically the onset parameters and wavelengths of the Faraday wave pattern under excitation with temporally asymmetric waveforms. A superposition of two sine waves with a mutual phase shift is used as excitation. Certain phase shifts give the possibility to generate time reversed shapes of the waveforms, in what we focus on here. The measurements are compared with numerical calculations based on the linear stability analysis of the full set of hydrodynamic equations for Newtonian liquids. We demonstrate with a modified Mathieu-equation the astonishing fact: already a linear system can be sensitive to the direction of the asymmetric, periodic excitation in terms of different thresholds amplitudes.