DOMAIN-WALLS IN WAVE PATTERNS

We study the interaction of counterpropagating traveling waves in 2D n onequilibrium media described by the complex Swift-Hohenberg equation (CSHE). Direct numerical integration of CSHE reveals novel features of domain walls separating wave systems: wave-vector selection and trans verse instability. Analytical treatment is based on a study of coupled complex Ginzburg-Landau equations for counterpropagating waves. At th e threshold we find the stationary (yet unstable) solution correspondi ng to the selected waves. It is shown that sources of traveling waves exhibit long wavelength instability, whereas sinks remain stable. An a nalogy with the Kelvin-Helmholtz instability is established.