Phononic Rogue Waves

TL;DR

This paper theoretically investigates the formation of rogue waves in phononic lattices, demonstrating how nonlinear models and initial conditions can produce localized extreme wave events in systems like FPUT lattices and granular crystals.

Contribution

It introduces a novel theoretical framework linking rogue wave phenomena to phononic lattices using NLS reduction and initial condition transformations.

Findings

Rogue wave-like dynamics can be initiated in FPUT lattices using Peregrine soliton solutions.

Gaussian initial data can produce rogue waves if sufficiently wide.

Granular crystals exhibit rogue wave dynamics, supporting potential experimental observation.

Abstract

We present a theoretical study of extreme events occurring in phononic lattices. In particular, we focus on the formation of rogue or freak waves, which are characterized by their localization in both spatial and temporal domains. We consider two examples. The first one is the prototypical nonlinear mass-spring system in the form of a homogeneous Fermi-Pasta-Ulam-Tsingou (FPUT) lattice with a polynomial potential. By deriving an approximation based on the nonlinear Schroedinger (NLS) equation, we are able to initialize the FPUT model using a suitably transformed Peregrine soliton solution of the NLS, obtaining dynamics that resembles a rogue wave on the FPUT lattice. We also show that Gaussian initial data can lead to dynamics featuring rogue wave for sufficiently wide Gaussians. The second example is a diatomic granular crystal exhibiting rogue wave like dynamics, which we also obtain through an NLS reduction and numerical simulations. The granular crystal (a chain of particles that interact elastically) is a widely studied system that lends itself to experimental studies. This study serves to illustrate the potential of such dynamical lattices towards the experimental observation of acoustic rogue waves.