Spiral destabilization by resonant forcing

¹ Max-Planck-Institut für Physik komplexer Systeme Nöthnitzer Str. 38, D-01187 Dresden, Germany
² Korea Institute for Advanced Study - Seoul 130-722, Korea

Received: 27 June 2003
Accepted: 5 January 2004

Abstract

Resonant forcing of an oscillatory medium has been found to cause irregular spatiotemporal patterns in experiments with a chemical reaction as well as in simulations of model equations. Focusing on the case, we show that one type of such chaotic patterns results from the destabilization of rotating spiral waves. For sufficiently large forcing amplitudes, subsequent fronts in wave trains emitted from the spiral core region start to attract each other, merge and occasionally trigger pairwise defect creation giving eventually rise to chaotic patterns. In a corresponding stability analysis, a novel merging instability of fronts is found and shown to be of convective nature. Upon further increase of the forcing, this instability becomes absolute and spirals are linearly unstable. In numerical simulations, spirals disintegrate in the region between the convective and absolute instability lines.