The FitzHugh–Nagumo equations are known to admit fast traveling pulse solutions with monotone tails. It is also known that this system admits traveling pulses with exponentially decaying oscillatory tails. Upon numerical continuation in parameter space, it has been observed that the oscillations in the tails of the pulses grow into a secondary excursion resembling a second copy of the primary pulse. In this paper, we outline in detail the geometric mechanism responsible for this single-to-double-pulse transition, and we construct the transition analytically using geometric singular perturbation theory and blow-up techniques.
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∗Received by the editors June 20, 2016; accepted for publication (in revised form) December 1, 2017; published electronically January 30, 2018. http://www.siam.org/journals/siads/17-1/M108070.html Funding: The work of the first author was supported by the NSF under grant DMS-1148284. The work of the second author was partially supported by the NSF through grant DMS-1408742. †Department of Mathematics, University of Arizona, Tucson, AZ 85721 (firstname.lastname@example.org). ‡Division of Applied Mathematics, Brown University, Providence, RI 02912 (Bjorn Sandstede@brown.edu).
- Geometric singular perturbation theory
- Traveling waves