On the locality of MHD turbulence scale fluxes

TL;DR

This paper investigates the scale locality of energy fluxes in MHD turbulence through numerical simulations, revealing smaller scaling exponents compared to hydrodynamic turbulence, and provides an in-depth analysis of total energy flux behavior.

Contribution

It introduces a spectral shell decomposition method to analyze MHD turbulence energy fluxes and identifies distinct scaling exponents for MHD compared to hydrodynamic turbulence.

Findings

Scaling exponents of 1/3 and 2/3 for MHD fluxes

Smaller exponents than hydrodynamic turbulence (4/3)

Detailed analysis of total energy flux

Abstract

The scale locality of energy fluxes for magnetohydrodynamics (MHD) is investigated numerically for stationary states of turbulence. Two types of forces are used to drive turbulence, a kinetic force that acts only on the velocity field and a kinetic-inductive forcing mechanism, which acts on the velocity and magnetic fields alike. The analysis is performed in spectral space, which is decomposed into a series of shells following a power law for the boundaries. The triadic transfers occurring among these shells are computed and the fluxes and locality functions are recovered by partial summation over the relevant shells. Employing Kraichnan locality functions, values of 1/3 and 2/3 for the scaling exponents of the four MHD energy fluxes are found. These values are smaller compared with the value of 4/3 found for hydrodynamic turbulence. To better understand these results, an in depth analysis is performed on the total energy flux.