Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Purely elastic linear instabilities in parallel shear flows with
  free-slip boundary conditions   We perform a linear stability analysis of viscoelastic plane Couette and
plane Poiseuille flows with free-slip boundary conditions. The fluid is
described by the Oldroyd-B constitutive model, and the flows are driven by a
suitable body force. We find that both types of flow become linearly unstable,
and we characterise the spatial structure of the unstable modes. By performing
a boundary condition homotopy from the free-slip to no-slip boundaries, we
demonstrate that the unstable modes are directly related to the least stable
modes of the no-slip problem, destabilised under the free-slip situation. We
discuss how our observations can be used to study recently discovered purely
elastic turbulence in parallel shear flows.

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The categories of this paper are: gr-qc
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The categories of this paper are: supr-con
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The categories of this paper are: hep-th
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The categories of this paper are: cond-mat
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The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
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The categories of this paper are: q-alg
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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org