On the transport and concentration of enstrophy in 3D magnetohydrodynamic turbulence

TL;DR

This paper investigates how enstrophy, related to vorticity and current in 3D magnetohydrodynamic turbulence, is transported across scales, showing a cascade process that concentrates enstrophy in small-scale structures.

Contribution

It formulates a physical-scale-based scenario demonstrating local, cascade-like enstrophy transfer in 3D MHD turbulence, aligning with observed small-scale concentration.

Findings

Enstrophy flux exhibits cascade-like properties.

Transport of enstrophy is from larger to smaller scales.

Enstrophy concentrates on small-scale structures.

Abstract

Working directly from the 3D magnetohydrodynamical equations and entirely in physical scales we formulate a scenario wherein the enstrophy flux exhibits cascade-like properties. In particular we show the inertially-driven transport of current and vorticity enstrophy is from larger to smaller scale structures and this inter-scale transfer is local and occurs at a nearly constant rate. This process is reminiscent of the direct cascades exhibited by certain ideal invariants in turbulent plasmas. Our results are consistent with the physically and numerically supported picture that current and vorticity concentrate on small-scale, coherent structures.