Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Partial invariants, large-scale dynamo action, and the inverse transfer
  of magnetic helicity   The existence of partially conserved enstrophy-like quantities is conjectured
to cause inverse energy transfers to develop embedded in magnetohydrodynamical
(MHD) turbulence, in analogy to the influence of enstrophy in two-dimensional
nonconducting turbulence. By decomposing the velocity and magnetic fields in
spectral space onto helical modes, we identify subsets of three-wave (triad)
interactions conserving two new enstrophy-like quantities which can be mapped
to triad interactions recently identified with facilitating large-scale
$\alpha$-type dynamo action and the inverse transfer of magnetic helicity. Due
to their dependence on interaction scale locality, the invariants suggest that
the inverse transfer of magnetic helicity might be facilitated by both local-
and nonlocal-scale interactions, and is a process more local than the
$\alpha$-dynamo. We test the predicted embedded (partial) energy fluxes by
constructing a shell model (reduced wave-space model) of the minimal set of
triad interactions (MTI) required to conserve the ideal MHD invariants.
Numerically simulated MTIs demonstrate that, for a range of forcing
configurations, the partial invariants are, with some exceptions, indeed useful
for understanding the embedded contributions to the total spectral energy flux.
Furthermore, we demonstrate that strictly inverse energy transfers may develop
if enstrophy-like conserving interactions are favoured, a mechanism recently
attributed to the energy cascade reversals found in nonconducting
three-dimensional turbulence subject to strong rotation or confinement. The
presented results have implications for the understanding of the physical
mechanisms behind large-scale dynamo action and the inverse transfer of
magnetic helicity, processes thought to be central to large-scale magnetic
structure formation.

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The categories of this paper are: cs
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
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The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: chao-dyn