Traveling?stripe forcing of oblique rolls in anisotropic systems

Abstract

The effects of a traveling, spatially periodic forcing are investigated in a system with axial anisotropy, where oblique stripe patterns occur at threshold in the unforced case and where the forcing wavenumber and the wavenumber of stripes are close to a 2:1 resonance. The forcing induces an interaction between the two degenerate oblique stripe orientations and for larger forcing amplitudes rectangular patterns are induced, which are dragged in phase by the forcing. With increasing forcing velocity a transition from a locked rectangular pattern to an unlocked superposition of a rectangular and oblique stripe pattern takes place. In this transition regime, especially when the ratio between the wavenumber of the forcing and that of the pattern deviates from the 2:1 ratio, surprisingly stable or long living complex patterns, such as zig–zag patterns and patterns including domain walls are found. Even more surprising is the observation, that such coherent structures propagate faster than the stripe forcing.