Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 2D Navier-Stokes system and no-slip boundary condition for vorticity in
  exterior domains   In this article we derive Biot-Savar law for exterior 2D domain. No-slip
condition in terms of vorticity is expressed in integral form. For
non-stationary fluid dynamics equations no-slip condition generates affine
invariant manifold and no-slip integral relations on vorticity can be
transferred to Robin-type boundary condition.

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The categories of this paper are: cs
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
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The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio