Bloch-front turbulence: theory and experiments

We report on experimental and theoretical findings of front destabilization that causes spontaneous spiral-vortex nucleation and produces a state of spatio-temporal disorder. The experiments were carried out on an oscillatory photosensitive Belousov-Zhabotinsky reaction that is periodically forced in time. Numerical studies were carried out on a modified Complex Ginzburg-Landau equation and on the FitzHugh-Nagumo model. Using velocity-curvature relations for fronts we associate the onset of spatio-temporal disorder with the Nonequilibrium Ising Bloch (NIB) bifurcation, and study the generic patterns that form on both sides of the bifurcation as the distance from it is increased.