Competition of spiral waves with anomalous dispersion in Couette-Taylor flow

We have investigated the generation of spiral waves in a Couette-Taylor system between counter rotating cylinders and found that for small supercriticality, the competition of spirals propagating in opposite directions along the axis of cylinders results in a formation of a localized source. Measuring the group velocity as a function of the amplitude, we have determined that these spirals have anomalous dispersion, in the sense that the phase and group velocity of each have opposite signs. The coupled complex Ginzburg-Landau equations offer a good theoretical framework to explain these results.