Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Intermittent turbulent dynamo at very low and high magnetic Prandtl
  numbers   Context: Direct numerical simulations have shown that the dynamo is efficient
even at low Prandtl numbers, i.e., the critical magnetic Reynolds number Rm_c
necessary for the dynamo to be efficient becomes smaller than the hydrodynamic
Reynolds number Re when Re -> infinity. Aims: We test the conjecture (Iskakov
et al. 2007) that Rm_c actually tends to a finite value when Re -> infinity,
and we study the behavior of the dynamo growth factor \gamma\ at very low and
high magnetic Prandtl numbers. Methods: We use local and nonlocal shell-models
of magnetohydrodynamic (MHD) turbulence with parameters covering a much wider
range of Reynolds numbers than direct numerical simulations, but of
astrophysical relevance. Results: We confirm that Rm_c tends to a finite value
when Re -> infinity. The limit for Rm -> infinity of the dynamo growth factor
\gamma\ in the kinematic regime behaves like Re^\beta, and, similarly, the
limit for Re -> infinity of \gamma\ behaves like Rm^{\beta'}, with
\beta=\beta'=0.4. Conclusion: Comparison with a phenomenology based on an
intermittent small-scale turbulent dynamo, together with the differences
between the growth rates in the different local and nonlocal models, indicate a
weak contribution of nonlocal terms to the dynamo effect.

35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph