Robust energy transfer mechanism and critically balanced turbulence via non-resonant triads in nonlinear wave systems

TL;DR

This paper uncovers a robust energy transfer process in nonlinear wave systems that favors non-resonant triads, leading to efficient turbulence at intermediate nonlinearity levels, with validation through analytical and numerical methods.

Contribution

It introduces a new energy transfer mechanism based on non-resonant triads and explains its efficiency at intermediate nonlinearities, supported by analytical and numerical evidence.

Findings

Maximum transfer efficiency occurs when frequency mismatch balances nonlinear frequency.

Turbulent cascades are most efficient at intermediate nonlinearity levels.

Numerical simulations confirm analytical predictions of the energy transfer mechanism.

Abstract

A robust energy transfer mechanism is found in nonlinear wave systems, which favours transfers towards modes interacting via non-resonant triads, applicable in meteorology, nonlinear optics and plasma wave turbulence. Transfer efficiency is maximal when the frequency mismatch of the non-resonant triad balances the system's nonlinear frequency: at intermediate levels of oscillation amplitudes an instability is triggered that explores unstable manifolds of periodic orbits, so turbulent cascades are most efficient at intermediate nonlinearity. Numerical simulations confirm analytical predictions.