Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Supersonic flow of a Bose-Einstein condensate past an oscillating
  attractive-repulsive obstacle   We investigate by numerical simulations the pattern formation after an
oscillating attractive-repulsive obstacle inserted into the flow of a
Bose-Einstein condensate. For slow oscillations we observe a complex emission
of vortex dipoles. For moderate oscillations organized lined up vortex dipoles
are emitted. For high frequencies no dipoles are observed but only lined up
dark fragments. The results shows that the drag force turns negative for
sufficiently high frequency. We also successfully model the {\it ship waves} in
front of the obstacle. In the limit of very fast oscillations all the
excitations of the system tend to vanish.

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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
30
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: plasm-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: math-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
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The categories of this paper are: alg-geom
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The categories of this paper are: q-bio
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The categories of this paper are: adap-org