Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Three-dimensional shear in granular flow   The evolution of granular shear flow is investigated as a function of height
in a split-bottom Couette cell. Using particle tracking, magnetic-resonance
imaging, and large-scale simulations we find a transition in the nature of the
shear as a characteristic height $H^*$ is exceeded. Below $H^*$ there is a
central stationary core; above $H^*$ we observe the onset of additional axial
shear associated with torsional failure. Radial and axial shear profiles are
qualitatively different: the radial extent is wide and increases with height
while the axial width remains narrow and fixed.

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The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
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The categories of this paper are: q-alg
1
The categories of this paper are: cs
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
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The categories of this paper are: stat
8
The categories of this paper are: hep-ex