Speaker
Description
Magnetized turbulence is ubiquitous in many astrophysical and terrestrial plasmas but no universal
theory exists. Even the detailed energy dynamics in magnetohydrodynamic turbulence are still not
well understood. We present a suite of ICM-like, subsonic, super-Alfvénic, high plasma-beta MHD turbulence
simulation that only vary in their dynamical range, i.e., in their separation between the large-scale
forcing and dissipation scales. From a practical point of view, we show how numerical dissipation can
be estimated using an energy transfer analysis framework and that implicit large eddy simulations
match direct numerical simulations. From a theoretical point of view, we use the same framework
to demonstrate that – contrary to hydrodynamic turbulence – the cross-scale energy fluxes are not
constant in MHD turbulence. This applies both to different mediators (such as cascade processes or
magnetic tension) for a given dynamical range as well as to a dependence on the dynamical range
itself. We do not observe any indication of convergence even at the highest resolution simulation at
2048^3 cells. This raises the question on whether an asymptotic regime in MHD turbulence exists, and,
if yes, what it looks like.
