Front reversals, wave traps, and twisted spirals in periodically forced oscillatory media.

Trapping of phase fronts and twisted spirals in periodically forced oscillatory media

Four-phase patterns in forced oscillatory systems

We investigate pattern formation in self-oscillating systems forced by an external periodic perturbation. Experimental observations and numerical studies of reaction-diffusion systems and an analysis of an amplitude equation are presented. The oscillations in each of these systems entrain to rational multiples of the perturbation frequency for certain values of the forcing frequency and amplitu...

Transition from oscillatory to excitable regime in a system forced at three times its natural frequency.

The effect of a temporal modulation at three times the critical frequency on a Hopf bifurcation is studied in the framework of amplitude equations. We consider a complex Ginzburg-Landau equation with an extra quadratic term, resulting from the strong coupling between the external field and the unstable modes. We show that, by increasing the intensity of the forcing, one passes from an oscillato...

BLOCH-front turbulence in a periodically forced Belousov-Zhabotinsky reaction.

Experiments on a periodically forced Belousov-Zhabotinsky chemical reaction show front breakup into a state of spatiotemporal disorder involving continual events of spiral-vortex nucleation and destruction. Using the amplitude equation for forced oscillatory systems and the normal form equations for a curved front line, we identify the mechanism of front breakup and explain the experimental obs...

Sinklike spiral waves in oscillatory media with a disk-shaped inhomogeneity.

Spiral wave propagation in oscillatory media with a disk-shaped inhomogeneity is examined. Depending on the properties of the medium as well as the inhomogeneity (different frequencies in two regions), distinct spiral waves including sinklike spirals and dense-sparse spirals, are able to emerge. We find that, unlike the previously found outward group velocity for spiral waves (normal spirals or...