Resonance drifts of spiral waves on media of periodic excitability.

Spiral waves subjected to an external periodic force exhibit very rich spatiotemporal dynamics including resonance attractors. In previous research, the modulation was mainly described as additional induced flow in the system, and a theory has been developed based on reducing the spiral wave dynamics to a low-dimensional map. In this paper, another perspective for study of the resonance attractors is suggested. The periodic modulation of excitability is directly described by the time dependence of the parameters. This approach gives us nice results that are well consistent with the experiments. Additionally, when we force the spiral with a frequency larger than its intrinsic frequency, another branch of spiral meandering with qualitatively different properties is observed. Full resonances are also clearly indicated. Furthermore, a kinetic model for spiral movement suggested in our previous paper is applied to this case. The theoretical results are in good quantitative agreement with numerical simulations. The model could be widely used in different excitable systems.