Cross-helically forced and decaying hydromagnetic turbulence. (arXiv:1901.05875v1 [physics.flu-dyn])
<a href="http://arxiv.org/find/physics/1/au:+Brandenburg_A/0/1/0/all/0/1">Axel Brandenburg</a> (Nordita), <a href="http://arxiv.org/find/physics/1/au:+Oughton_S/0/1/0/all/0/1">Sean Oughton</a> (University of Waikato)
We study the evolution of kinetic and magnetic energy spectra in
magnetohydrodynamic flows in the presence of strong cross helicity. For forced
turbulence, we find weak inverse transfer of kinetic energy toward the smallest
wavenumber. This is plausibly explained by the finiteness of scale separation
between the injection wavenumber and the smallest wavenumber of the domain,
which here is a factor of 15. In the decaying case, there is a slight increase
at the smallest wavenumber, which is probably explained by the dominance of
kinetic energy over magnetic energy at the smallest wavenumbers. Within a range
of wavenumbers covering almost an order of magnitude the decay is purely
exponential, which is argued to be a consequence of a suppression of
nonlinearity due to the presence of strong cross helicity.
We study the evolution of kinetic and magnetic energy spectra in
magnetohydrodynamic flows in the presence of strong cross helicity. For forced
turbulence, we find weak inverse transfer of kinetic energy toward the smallest
wavenumber. This is plausibly explained by the finiteness of scale separation
between the injection wavenumber and the smallest wavenumber of the domain,
which here is a factor of 15. In the decaying case, there is a slight increase
at the smallest wavenumber, which is probably explained by the dominance of
kinetic energy over magnetic energy at the smallest wavenumbers. Within a range
of wavenumbers covering almost an order of magnitude the decay is purely
exponential, which is argued to be a consequence of a suppression of
nonlinearity due to the presence of strong cross helicity.
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