Abstract

Recently, for Navier-Stokes turbulence, an exact decomposition of the energy flux across scales has been derived; this identifies the flux contributions associated with vortex stretching and strain self-amplification. In the context of large-scale structure formation, it identifies the physical processes related to inverse cascades in turbulent flows. Here, we extend the formalism to general coupled advection-diffusion equations. The resulting flux decompositions can be readily applied to problems involving the dynamics of active and passive scalars and vectors. We use the method to calculate magnetic and kinetic energy fluxes for magnetohydrodynamic (MHD) turbulence. The aim is to disentangle and quantify the relative contributions of current-sheet thinning by vorticity gradients and strain-current coupling to the energy cascade in MHD . I would like to discuss to what extent this approach can be leveraged especially in the plasma context on various levels of fluid approximations.