Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hydrodynamics of Internal Shocks in Relativistic Outflows   We study the hydrodynamical effects of two colliding shells, adopted to model
internal shocks in various relativistic outflows such as gamma-ray bursts and
blazars. We find that the density profiles are significantly affected by the
propagation of rarefaction waves. A split-feature appears at the contact
discontinuity of the two shells. The shell spreading with a few ten percent of
the speed of light is also shown to be a notable aspect. The conversion
efficiency of the bulk kinetic energy to internal one shows deviations from the
widely-used inelastic two-point-mass-collision model. Observational
implications are also shortly discussed.

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The categories of this paper are: physics
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The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
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The categories of this paper are: acc-phys
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The categories of this paper are: supr-con
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ex
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The categories of this paper are: stat
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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: nlin
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The categories of this paper are: hep-lat