Spectral Modeling of Magnetohydrodynamic Turbulent Flows

TL;DR

This paper introduces a spectral model for simulating incompressible MHD turbulence, extending classical LES approaches to better capture non-Kolmogorov spectra and improve agreement with direct numerical simulations.

Contribution

It develops a novel spectral LES model for MHD that incorporates general spectra and eddy noise, enhancing simulation accuracy for dynamo studies.

Findings

Improved agreement with DNS results using the new eddy-damping time.

Model effectively captures non-Kolmogorov spectra in MHD turbulence.

Enhances the simulation of magnetic field dynamics in MHD flows.

Abstract

We present a dynamical spectral model for Large Eddy Simulation of the incompressible magnetohydrodynamic (MHD) equations based on the Eddy Damped Quasi Normal Markovian approximation. This model extends classical spectral Large Eddy Simulations for the Navier-Stokes equations to incorporate general (non Kolmogorovian) spectra as well as eddy noise. We derive the model for MHD and show that introducing a new eddy-damping time for the dynamics of spectral tensors in the absence of equipartition between the velocity and magnetic fields leads to better agreement with direct numerical simulations, an important point for dynamo computations.