The effect of subgrid-scale models on grid-scale/subgrid-scale energy transfers in large-eddy simulation of incompressible magnetohydrodynamic turbulence

In this work, the accuracy of various models used in large-eddy simulations (LES) of incompressible magnetohydrodynamic (MHD) turbulence is evaluated. Particular attention is devoted to the capabilities of models to reproduce the transfers between resolved grid-and subgrid-scales. The exact global balance of MHD turbulent flows is first evaluated from direct numerical simulation (DNS) database. This balance is controlled by the transfers between scales and between kinetic and magnetic energies. Two cases of forced homogeneous isotropic MHD turbulent flows are considered, with and without injecting large scale helicity. The strong helical case leads to domination of the magnetic energy due to an inverse cascade [A. Brandenburg, Astrophys. J. 550(2), 824 (2001); N. E. Haugen et al., Phys. Rev. E 70(1), 016308 (2004)]. The energy transfers predicted by various models are then compared with the transfer extracted from DNS results. This allows to discriminate models classically used for LES of MHD turbulence. In the non-helical case, the Smagorinsky-like model [M. L. Theobald et al., Phys. Plasmas 1, 3016 (1994)] and a mixed model are able to perform stable LES, but the helical case is a more demanding test and all the models lead to unstable simulations. Published by AIP Publishing.