Open AccessWiggly canards: Growth of traveling wave trains through a family of fast-subsystem foci
Author(s) -
Paul Carter,
Alan R Champneys
Publication year - 2022
Publication title -
discrete and continuous dynamical systems. series s
Language(s) - English
Resource type - Journals
eISSN - 1937-1632
pISSN - 1937-1179
DOI - 10.3934/dcdss.2022036
Subject(s) - saddle , mathematical analysis , hopf bifurcation , eigenvalues and eigenvectors , amplitude , orbit (dynamics) , slow manifold , parameter space , bifurcation , physics , focus (optics) , mathematics , manifold (fluid mechanics) , singular perturbation , geometry , quantum mechanics , optics , mathematical optimization , nonlinear system , engineering , aerospace engineering , mechanical engineering
A class of two-fast, one-slow multiple timescale dynamical systems is considered that contains the system of ordinary differential equations obtained from seeking travelling-wave solutions to the FitzHugh-Nagumo equations in one space dimension. The question addressed is the mechanism by which a small-amplitude periodic orbit, created in a Hopf bifurcation, undergoes rapid amplitude growth in a small parameter interval, akin to a canard explosion . The presence of a saddle-focus structure around the slow manifold implies that a single periodic orbit undergoes a sequence of folds as the amplitude grows. An analysis is performed under some general hypotheses using a combination ideas from the theory of canard explosion and Shilnikov analysis. An asymptotic formula is obtained for the dependence of the parameter location of the folds on the singular parameter and parameters that control the saddle focus eigenvalues. The analysis is shown to agree with numerical results both for a synthetic normal-form example and the FitzHugh-Nagumo system.