Numerical continuation of spiral waves in heteroclinic networks of cyclic dominance

TL;DR

This paper develops a numerical continuation method for analyzing heteroclinic-induced spiral waves in reaction-diffusion systems with cyclic dominance, enabling efficient computation on full disks and larger networks.

Contribution

It introduces a low-dimensional Fourier-based boundary-value problem approach with novel boundary conditions for spiral wave continuation in heteroclinic networks.

Findings

Successfully computed spiral waves in a three-species model.

Extended the method to larger networks with five competing species.

Demonstrated efficient continuation on full disk domains.

Abstract

Heteroclinic-induced spiral waves may arise in systems of partial differential equations that exhibit robust heteroclinic cycles between spatially uniform equilibria. Robust heteroclinic cycles arise naturally in systems with invariant subspaces and their robustness is considered with respect to perturbations that preserve these invariances. We make use of particular symmetries in the system to formulate a relatively low-dimensional spatial two-point boundary-value problem in Fourier space that can be solved efficiently in conjunction with numerical continuation. The standard numerical set-up is formulated on an annulus with small inner radius, and Neumann boundary conditions are used on both inner and outer radial boundaries. We derive and implement alternative boundary conditions that allow for continuing the inner radius to zero and so compute spiral waves on a full disk. As our primary example, we investigate the formation of heteroclinic-induced spiral waves in a reaction-diffusion model that describes the spatiotemporal evolution of three competing populations in a two-dimensional spatial domain--much like the Rock-Paper-Scissors game. We further illustrate the efficiency of our method with the computation of spiral waves in a larger network of cyclic dominance between five competing species, which describes the so-called Rock-Paper-Scissors-Lizard-Spock game.