Periodic forcing of spiral waves in excitable media.

An analysis of periodically forced spiral waves in excitable media provides a simple explanation of the resonant drift dynamics and frequency entrainments observed both in laboratory experiments and in simulations of partial-differential equations. Forcing of both rigidly rotating and meandering spirals is considered. In the meandering case we predict the existence of different resonant drift states that could be detected in experiments. \textcopyright{} 1996 The American Physical Society.