COUNTERPROPAGATING PERIODIC PULSES IN COUPLED GINZBURG-LANDAU EQUATIONS

A recently observed stable regime in the form of periodically collidin g counterpropagating wave packets (pulses) in an annular convection ch annel at very small positive overcriticalities is described analytical ly in terms of coupled Ginzburg-Landau equations. First, the existence of this regime is demonstrated in the framework of the simplest syste m including only the group-velocity difference, weak gain, and nonline ar dissipative coupling between two modes. In this approximation, the shape of the counterpropagating waves remains indefinite. It is demons trated that additional dispersive terms, regarded as a small perturbat ion, provide shaping of the wave packets and also give rise to the dev iation of the phase velocity from that for purely linear waves.