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DY: Fachverband Dynamik und Statistische Physik

DY 21: Pattern Formation

DY 21.2: Vortrag

Mittwoch, 2. April 2014, 15:15–15:30, HÜL 186

Orientational selection in pattern formation by traveling modulations — •Lisa Rapp¹, Vanessa Weith¹, Alexei Krekhov^1,2, and Walter Zimmermann¹ — ¹Theoretische Physik, 95440 Universität Bayreuth, Germany — ²Max-Planck-Institut für Dynamik und Selbstorganisation, 37077 Göttingen, Germany

Often disordered stripe patterns occur in two-dimensional isotropic systems, such as in reaction diffusion systems, in thermal convection or in block copolymers. We suggest an effective approach to control the pattern morphology by applying a traveling long-wave periodic modulation of the control parameter of the pattern forming system. The model systems we investigate include the Swift-Hohenberg, the evolution equation for microphase separation in symmetric diblock copolymers and the Lengyel-Epstein model for chemical reactions. Studying the onset of the stripe phase we find that depending on the traveling velocity v different orientations of the stripes with respect to the modulation may be favoured near threshold. In case of a stationary modulation the wave vector of the stripes is preferentially perpendicular to the wave vector of the forcing. This also holds for velocities smaller than a velocity v1. For velocities larger than a velocity v2 a parallel orientation of the wave vectors has the lowest threshold. In the intermediate range v1 < v < v2 both wave vectors adjust themselves at an angle between 0 and π/2.