Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Stirring faces: mixing in a quiescent fluid   This fluid dynamics video depicts the mixing that occurs as a two-dimensional
flat plate plunges sinusoidally in a quiescent fluid. Finite-time Lyapunov
exponents reveal sets that are attracting or repelling. As the flow field
develops, strange faces emerge.

32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio