Spatially Extended Dislocations Produced by the Dispersive Swift-Hohenberg Equation

TL;DR

This paper investigates the dispersive Swift-Hohenberg equation, revealing how it produces stripe patterns with extended dislocations called seam defects, and establishes analytical links to spiral waves in the anisotropic complex Ginzburg-Landau equation.

Contribution

It introduces the dispersive Swift-Hohenberg equation and analytically connects seam defects to spiral waves, providing formulas for their velocities and organization.

Findings

Seam defects correspond to spiral waves in the ACGLE.

Analytical formulas for spiral core velocity and spacing.

Numerical results confirm analytical predictions.

Abstract

Motivated by previous results showing that the addition of a linear dispersive term to the two-dimensional Kuramoto-Sivashinsky equation has a dramatic effect on the pattern formation, we study the Swift-Hohenberg equation with an added linear dispersive term, the dispersive Swift-Hohenberg equation (DSHE). The DSHE produces stripe patterns with spatially extended dislocations that we call seam defects. In contrast to the dispersive Kuramoto-Sivashinsky equation, the DSHE has a narrow band of unstable wavelengths close to an instability threshold. This allows for analytical progress to be made. We show that the amplitude equation for the DSHE close to threshold is a special case of the anisotropic complex Ginzburg-Landau equation (ACGLE) and that seams in the DSHE correspond to spiral waves in the ACGLE. Seam defects and the corresponding spiral waves tend to organize themselves into chains, and we obtain formulas for the velocity of the spiral wave cores and for the spacing between them. In the limit of strong dispersion, a perturbative analysis yields a relationship between the amplitude and wavelength of a stripe pattern and its propagation velocity. Numerical integrations of the ACGLE and the DSHE confirm these analytical results.