SYMMETRY-BREAKING IN NONEQUILIBRIUM SYSTEMS - INTERACTION OF DEFECTS

The dynamics of defects against the background of a regular system of rolls is investigated within the Swift-Hohenberg model with periodically-space-modulated pumping. For thermal convection, this corresponds to periodic nonuniform beating. Amplitude equations obtained for a parametric-resonance case generalize the equations derived earlier and describe both longitudinal and transverse defects. It is shown that a pair of longitudinal defects either attract one another until they annihilate or they diverge to infinity. Transverse defects are able to form bound static states. We investigate the influence of small nongradient effects on the dynamics of single longitudinal and transverse defects as well as on their interaction. We also discuss the effect of ''elastic'' scattering of transverse defects on each other in the presence of small dispersion.