Drift of spiral waves in excitable media

The motion of a spiral wave in excitable media due to interaction with various kinds of boundaries is considered both in the case of small diffusion of the slow field and for the diffusionless case. The drift of the core and the frequency shift of the spiral due to distant boundaries or inhomogeneities in the media are found to be a superexponentially weak function of the distance from the core. It is shown that for some range of parameters the spiral drifts away from the center of a circular domain. It is also shown that the spiral can form a bound state with a plane boundary as well as with a small topological defect. Numerical simulations are performed demonstrating qualitative agreement with the analytical results.