Numerical methods for steady state/Hopf mode interactions

Numerical methods for dealing with steady state/Hopf mode interactions using extended systems are considered. In particular, it is shown that such a mode interaction corresponds to a symmetric breaking bifurcation of a Hopf extended system as well as a Hopf bifurcation of a symmetric breaking extended system. Non-degeneracy conditions associated with these bifurcations are derived and interpreted in the context of the mode interaction. The alternative approach of using a single test function instead of a full extended system is considered in detail in one of the casses. Numerical results for a two-parameter version of the Kuramoto-Sivashinsky equation are presented to illustrate the theory.