Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Numerical Analysis of Time-Dependent Galbrun Equation in an Infinite
  Duct   In this paper we are interested in the mathematical and numerical analysis of
the time-dependent Galbrun equa- tion in a rigid duct. This equation models the
acoustic propagation in presence of flow [1]. We propose a regu- larized
variational formulation of the problem, in the sub- sonic case, suitable for an
approximation by Lagrange finite elements, and corresponding absorbing boundary
conditions.

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The categories of this paper are: astro-ph
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The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
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The categories of this paper are: alg-geom
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: quant-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: stat
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The categories of this paper are: hep-th