Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlinear Development of Thermal Instability without External Forcing   Supersonic turbulent motions are the remarkable properties of interstellar
medium. Previous numerical simulations have demonstrated that the thermal
instability in a shock-compressed layer produces the supersonic turbulent
motion that does not decay. In this paper we focus on two- and
three-dimensional numerical simulations of the non-linear development of simple
thermal instability incorporating physical viscosity but without any external
forcing, in order to isolate the effects of various processes responsible for
the long-lasting turbulent motion. As the initial condition for our
simulations, we set up spatially uniform gas with thermally unstable
temperature in a box with periodic boundaries. After the linear growth stage of
the thermal instability, two-phase medium forms where cold clumps are embedded
in warm medium, and turbulent fluid flow clearly visible as translational
motions of the cold clumps does not decay in a viscous dissipation timescale.
The amplitude of the turbulent velocity increases when we reduce the Prandtl
number that is the non-dimensional ratio of kinetic viscosity to thermal
conduction: the saturation amplitude does not change when we increase the
viscosity and thermal conduction coefficients simultaneously in order to keep
the Prandtl number. This shows that the thermal conduction plays an important
role in maintaining turbulent motions against viscous dissipation. The
amplitude also increases when we increase the ratio of the computational domain
length $L$ to the cooling length $\lambda_{\rm c}$ that is defined by the
product of the cooling time and the sound speed, as long as $L \la 100
\lambda_{\rm c}$.

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The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
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The categories of this paper are: bayes-an
1
The categories of this paper are: cs
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The categories of this paper are: chao-dyn
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The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
9
The categories of this paper are: nlin