Chaotic Resonant Dynamics and Exchanges of Energy in Hamiltonian PDEs

TL;DR

This paper demonstrates the existence of solutions in certain nonlinear PDEs on a 2D torus that exhibit chaotic-like energy exchanges among Fourier modes, using heteroclinic connections and symbolic dynamics.

Contribution

It introduces a novel method to construct solutions with chaotic energy transfer in Hamiltonian PDEs via heteroclinic connections and symbolic dynamics.

Findings

Existence of solutions with chaotic energy exchanges in nonlinear PDEs.

Construction of heteroclinic connections between invariant objects.

Development of symbolic dynamics (Smale horseshoe) for the Birkhoff Normal Form.

Abstract

The aim of this note is to present the recent results in [16] where we provide the existence of solutions of some nonlinear resonant PDEs on the 2-dimensional torus exchanging energy among Fourier modes in a \emph{chaotic-like} way. We say that a transition of energy is \emph{chaotic-like} if either the choice of activated modes or the time spent in each transfer can be chosen randomly. We consider the nonlinear cubic Wave, the Hartree and the nonlinear cubic Beam equations. The key point of the construction of the special solutions is the existence of heteroclinic connections between invariant objects and the construction of symbolic dynamics (a Smale horseshoe) for the Birkhoff Normal Form of those equations.