Spatio temporal analysis of waves in compressively driven magnetohydrodynamics turbulence

TL;DR

This study uses direct numerical simulations to analyze wave interactions in compressively driven magnetohydrodynamic turbulence, identifying wave modes and their energy distribution under various plasma conditions.

Contribution

The paper introduces a detailed spatio-temporal spectral analysis method to quantify wave mode energies in compressible MHD turbulence, revealing the dominance of nonlinear dynamics.

Findings

Identification of Alfvén and magnetosonic waves in turbulence

Quantification of energy in wave modes as a function of parameters

Nonlinear plasma dynamics dominate despite wave presence

Abstract

Using direct numerical simulations (DNSs), the interaction between linear waves and turbulence under the compressible magnetohydrodynamic (CMHD) approach was studied. A set of DNSs in three dimensions for a spatial resolution of $128^3$ and $256^3$ were performed. A parametric study was carried out varying the sonic Mach number, the mean magnetic field and the compressibility amplitude of the forcing. Spatio-temporal spectra of the magnetic energy were built and analyzed, allowing for direct identification of all wave modes in a CMHD turbulent system and quantification of the amount of energy in each mode as a function of the wave number. Thus, linear waves were detected, that is Alfv\'en waves and fast and slow magnetosonic waves. Furthermore, different responses of the plasma were found according to whether the Mach number or the mean magnetic field was varied. On the other hand, making use of spatio-temporal spectra and two different integration methods, we accurately quantified the amount of energy present in each of the normal modes. Finally, although the presence of linear waves was observed, in all the cases studied the system was mainly dominated by the non-linear dynamics of the plasma.