Strong Imbalanced Turbulence

TL;DR

This paper investigates strong imbalanced MHD Alfvenic turbulence, revealing anisotropy differences between weak and strong waves, and proposes an amended critical balance concept to better understand energy cascades in such systems.

Contribution

It introduces a revised critical balance framework that accounts for imbalanced turbulence, extending previous models to include anisotropy differences and self-similar energy cascade solutions.

Findings

Anisotropy of weak waves exceeds that of strong waves.

Revised critical balance incorporates a propagation argument.

Discussion of self-similar solutions in driven turbulence.

Abstract

We consider stationary, forced, imbalanced, or cross-helical MHD Alfvenic turbulence where the waves traveling in one direction have higher amplitudes than the opposite waves. This paper is dedicated to so-called strong turbulence, which cannot be treated perturbatively. Our main result is that the anisotropy of the weak waves is stronger than the anisotropy of a strong waves. We propose that critical balance, which was originally conceived as a causality argument, has to be amended by what we call a propagation argument. This revised formulation of critical balance is able to handle the imbalanced case and reduces to old formulation in the balanced case. We also provide phenomenological model of energy cascading and discuss possibility of self-similar solutions in a realistic setup of driven turbulence.