Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Geometric Stability of Pseudo-plane Ideal Flows   Geometric analysis of steady pseudo-plane ideal flow reveals a fundamental
relation between vertical coherence and streamline topology. It shows vertical
alignment only exists in straightline jet and circular vortex. A geometric
stability theory is then developed as a structural stability in contrast to
traditional dynamical stability, suggesting all vertical-aligned pseudo-plane
flows are geometrically stable and all non-aligned non-straightline flows are
unstable. It provides a topological explanation for the tendency of
axisymmetrization and vertical alignment observed in vortex experiments.

2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
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The categories of this paper are: stat
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The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-lat
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The categories of this paper are: q-bio
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The categories of this paper are: econ
13
The categories of this paper are: quant-ph
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The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con