Large-scale magnetic dynamos in non-helical and helical flows and a generalized quenching formalism. (arXiv:1905.01256v1 [physics.flu-dyn])
<a href="http://arxiv.org/find/physics/1/au:+Zhou_H/0/1/0/all/0/1">Hongzhe Zhou</a>, <a href="http://arxiv.org/find/physics/1/au:+Blackman_E/0/1/0/all/0/1">Eric G. Blackman</a>
For ideal MHD, we analytically show that both helical and non-helical
anisotropic velocity flows which dynamo amplify large-scale magnetic fields,
also grow large-scale magnetic helicity. We then derive a new generalized
quenching formalism for these large-scale dynamos. This formalism implies that
the widely used dynamical quenching from magnetic helicity conservation applies
only for isotropic helical flows, for which the dynamo coefficients depend only
on a part of the Lorentz force that survives the isotropization.
For ideal MHD, we analytically show that both helical and non-helical
anisotropic velocity flows which dynamo amplify large-scale magnetic fields,
also grow large-scale magnetic helicity. We then derive a new generalized
quenching formalism for these large-scale dynamos. This formalism implies that
the widely used dynamical quenching from magnetic helicity conservation applies
only for isotropic helical flows, for which the dynamo coefficients depend only
on a part of the Lorentz force that survives the isotropization.
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