Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Doubly-periodic array of bubbles in a Hele-Shaw cell   Exact solutions are presented for a doubly-periodic array of steadily moving
bubbles in a Hele-Shaw cell when surface tension is neglected. It is assumed
that the bubbles either are symmetrical with respect to the channel centreline
or have fore-and-aft symmetry, or both, so that the relevant flow domain can be
reduced to a simply connected region. By using conformal mapping techniques, a
general solution with any number of bubbles per unit cell is obtained in
integral form. Several examples are given, including solutions for multi-file
arrays of bubbles in the channel geometry and doubly-periodic solutions in an
unbounded cell.

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The categories of this paper are: hep-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: q-bio
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The categories of this paper are: nlin
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The categories of this paper are: cs
27
The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: ao-sci
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The categories of this paper are: stat
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The categories of this paper are: funct-an
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The categories of this paper are: math-ph
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The categories of this paper are: hep-lat