Bonn 2020 – scientific programme
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EP: Fachverband Extraterrestrische Physik
EP 3: Poster session
EP 3.2: Poster
Tuesday, March 31, 2020, 16:30–18:30, Zelt
Magnetic helicity inverse transfer in supersonic isothermal MHD turbulence — •Jean-Mathieu Teissier1, 3 and Wolf-Christian Müller1,2,3 — 1Technische Univesität Berlin, ER3-2, Hardenbergstr. 36a, D-10623 Berlin, German — 2Max-Planck/Princeton Center for Plasma Physics — 3Berlin International Graduate School in Model and Simulation Based Research
Magnetic helicity is an ideal invariant of the magnetohydrodynamic (MHD) equations which exhibits an inverse transfer in spectral space. Up to the present day, its transport has been studied in direct numerical simulations only in incompressible or in subsonic or transonic flows. Inspired by typical values of the turbulent root mean square (RMS) Mach number in the interstellar medium, this work presents some aspects of the magnetic helicity inverse transfer in high Mach number isothermal compressible turbulence, with RMS Mach numbers up to the order of ten:
1) a clear Mach-number dependence of the spectral magnetic helicity scaling but an invariant scaling exponent of the co-spectrum of the Alfvén velocity and its curl,
2) the approximate validity of a dynamical balance relation found by incompressible turbulence closure theory,
3) a characteristic structuring of helically-decomposed nonlinear shell-to-shell fluxes that can be disentangled into different spectrally local and non-local transfer processes.