Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spout States in the Selective Withdrawal System   In selective withdrawal, fluid is withdrawn through a nozzle suspended above
the flat interface separating two immiscible, density-separated fluids of
viscosities $\nu_{upper}$ and $\nu_{lower} = \lambda \nu_{upper}$. At low
withdrawal rates, the interface gently deforms into a hump. At a transition
withdrawal rate, a spout of the lower fluid becomes entrained with the flow of
the upper one into the nozzle. When $\lambda = 0.005$, the spouts at the
transition are very thin with features that are over an order of magnitude
smaller than any observed in the humps. When $\lambda = 20$, there is an
intricate pattern of hysteresis and a spout appears which is qualitatively
different from those seen at lower $\lambda$. No corresponding qualitative
difference is seen in the hump shapes.

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The categories of this paper are: hep-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: q-alg
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The categories of this paper are: econ
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: gr-qc
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The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
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The categories of this paper are: bayes-an
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The categories of this paper are: eess