Nonhelical turbulence and the inverse transfer of energy: A parameter
  study
  We explore the phenomenon of the recently discovered inverse transfer of
energy from small to large scales in decaying magnetohydrodynamical turbulence
by Brandenburg et al. (2015) even for nonhelical magnetic fields. For this
investigation we mainly employ the Pencil-Code performing a parameter study,
where we vary the Prandtl number, the kinematic viscosity and the initial
spectrum. We find that in order to get a decay which exhibits this inverse
transfer, large Reynolds numbers ($\mathcal{O}\sim 10^{3}$) are needed and low
Prandtl numbers of the order unity $Pr = 1$ are preferred. Compared to helical
MHD turbulence, though, the inverse transfer is much less efficient in
transferring magnetic energy to larger scales than the well-known effect of the
inverse cascade. Hence, applying the inverse transfer to the magnetic field
evolution in the Early Universe, we question whether the nonhelical inverse
transfer is effective enough to explain the observed void magnetic fields if a
magneto- genesis scenario during the electroweak phase transition is assumed.
