Noise-induced Brownian motion of spiral waves - art. no. 046205

We study the erratic displacement of spiral waves forced to move in a mediu m with random spatiotemporal excitability. Analytical work and numerical si mulations are performed in relation to a kinematic scheme, assumed to descr ibe the autowave dynamics for weakly excitable systems. Under such an appro ach, the Brownian character of this motion is proved and the corresponding dispersion coefficient is evaluated. This quantity shows a nontrivial depen dence on the temporal and spatial correlation parameters of the external fl uctuations. In particular, a resonantlike behavior is neatly evidenced in t erms of the noise correlation time for the particular situation of spatiall y uniform fluctuations. Actually, this case turns out to be, to a large ext ent, exactly solvable, whereas a pair of dispersion mechanisms are discusse d qualitatively and quantitatively to explain the results for the more gene ral scenario of spatiotemporal disorder.