Diffusive Propagation of Energy in a Non-Acoustic Chain

Abstract

We consider a non acoustic chain of harmonic oscillators with the dynamics perturbed by a random local exchange of momentum, such that energy and momentum are conserved. The macroscopic limits of the energy density, momentum and the curvature (or bending) of the chain satisfy a system of evolution equations}. We prove that, in a diffusive space-time scaling, the curvature and momentum evolve following a linear system that corresponds to a damped Euler-Bernoulli beam equation. The macroscopic energy density evolves following a non linear diffusive equation. In particular the energy transfer is diffusive in this dynamics. This provides a first rigorous example of a normal diffusion of energy in a one dimensional dynamics that conserves the momentum.

References in corpus (3)

• A momentum conserving model with anomalous thermal conductivity in low dimension
• Energy transport in stochastically perturbed lattice dynamics
• Ballistic and superdiffusive scales in macroscopic evolution of a chain of oscillators

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• 5/6-Superdiffusion of energy for coupled charged harmonic oscillators in a magnetic field