Published online by Cambridge University Press: 09 June 2010
Spatiotemporal patterns near a codimension-2 Turing-Hopf point of the one-dimensionalsuperdiffusive Brusselator model are analyzed. The superdiffusive Brusselator modeldiffers from its regular counterpart in that the Laplacian operator of the regular modelis replaced by ∂ α /∂|ξ|α , 1 < α< 2, an integro-differential operator that reflects the nonlocal behavior ofsuperdiffusion. The order of the operator, α, is a measure of the rate ofsuperdiffusion, which, in general, can be different for each of the two components. Aweakly nonlinear analysis is used to derive two coupled amplitude equations describing theslow time evolution of the Turing and Hopf modes. We seek special solutions of theamplitude equations, namely a pure Turing solution, a pure Hopf solution, and a mixed modesolution, and analyze their stability to long-wave perturbations. We find that thestability criteria of all three solutions depend greatly on the rates of superdiffusion ofthe two components. In addition, the stability properties of the solutions to theanomalous diffusion model are different from those of the regular diffusion model.Numerical computations in a large spatial domain, using Fourier spectral methods in spaceand second order Runge-Kutta in time are used to confirm the analysis and also to findsolutions not predicted by the weakly nonlinear analysis, in the fully nonlinear regime.Specifically, we find a large number of steady state patterns consisting of a localizedregion or regions of stationary stripes in a background of time periodic cellular motion,as well as patterns with a localized region or regions of time periodic cells in abackground of stationary stripes. Each such pattern lies on a branch of such solutions, isstable and corresponds to a different initial condition. The patterns correspond to thephenomenon of pinning of the front between the stripes and the time periodic cellularmotion. While in some cases it is difficult to isolate the effect of the diffusionexponents, we find characteristics in the spatiotemporal patterns for anomalous diffusionthat we have not found for regular (Fickian) diffusion.
This paper is dedicated to the memory of our colleague and friend Alexander (Sasha)Golovin