Dresden 2014 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 21: Pattern Formation

DY 21.6: Talk

Wednesday, April 2, 2014, 16:15–16:30, HÜL 186

Pattern formation in anisotropic systems with modulation: stripes versus defects — •Badr Kaoui, Achim Guckenberger, Falko Ziebert, Alexei Krekhov, and Walter Zimmermann — Theoretical Physics I, University of Bayreuth, 95440 Bayreuth, Germany

A new symmetry class of pattern formation is investigated, having an anisotropy direction and a modulation perpendicular to the former. An example for this situations is the wrinkle pattern that forms during the relaxation of a deposited thin solid film (e.g. oxide) on a stretched soft substrate (e.g. a PDMS elastomer). If the substrate elastic properties are anisotropic perpendicular to the direction of prestretching, beyond a critical modulation strength, a fascinating competition occurs between the emergence of perfect regular stripes and wrinkles including branching defects. Using pseudo-spectral simulations and linear stability analysis we show how spatial modulations induce a wave-number band of patterns including various defect orders. We found unexpectedly the existence of a band of stable defect free stripe patterns and we predicted when and how these stripes bifurcate from the defect and flat ground states. Related universal phase diagrams are drawn with possible applications to the wrinkles system and the dissipative counterpart of the electroconvection in nematic liquid crystals.