Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Numerical study of dynamo action at low magnetic Prandtl numbers   We present a three--pronged numerical approach to the dynamo problem at low
magnetic Prandtl numbers $P_M$. The difficulty of resolving a large range of
scales is circumvented by combining Direct Numerical Simulations, a
Lagrangian-averaged model, and Large-Eddy Simulations (LES). The flow is
generated by the Taylor-Green forcing; it combines a well defined structure at
large scales and turbulent fluctuations at small scales. Our main findings are:
(i) dynamos are observed from $P_M=1$ down to $P_M=10^{-2}$; (ii) the critical
magnetic Reynolds number increases sharply with $P_M^{-1}$ as turbulence sets
in and then saturates; (iii) in the linear growth phase, the most unstable
magnetic modes move to small scales as $P_M$ is decreased and a Kazantsev
$k^{3/2}$ spectrum develops; then the dynamo grows at large scales and modifies
the turbulent velocity fluctuations.

21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
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The categories of this paper are: solv-int
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The categories of this paper are: stat
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-th
2
The categories of this paper are: math
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The categories of this paper are: eess
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The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: funct-an