Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dynamically forced cells of a viscoelastic fluid over an array of
  rollers   Our fluid dynamics video shows the response of a layer of viscoelastic fluid
to an array of four-roll mills steadily rotating underneath. When the
relaxation time of the fluid is sufficiently long, the fluid divides into
"cells" with a convex free surface above the site of each roller. This is
reminiscent of the rod-climbing effect. On this relaxation time-scale, the flow
also transitions from being initially Newtonian-like to one where the fluids'
elasticity plays a dynamical role: The fluid cells oscillate with regularity in
position and shape on a timescale much longer than the relaxation time. As the
relaxation time is further increased, the cells become less localized to the
underlying rollers, and their now irregular oscillations reflect the presence
of many frequencies.

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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: mtrl-th
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
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The categories of this paper are: q-fin
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
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The categories of this paper are: chao-dyn
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The categories of this paper are: gr-qc
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The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
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The categories of this paper are: adap-org