Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bifurcation induced by the aspect ratio in a turbulent Von-K\'arm\'an
  swirling flow   We evaluate the effect of two experimental parameters on the slow dynamics of
a Von-K\'arm\'an swirling flow driven by two propellers in a closed cylinder.
The first parameter is the inertia mo- mentum of the propellers, and the second
parameter is the aspect ratio, i.e. the distance between the propellers $H$
divided by the diameter $D$. We use a cell with a fixed diameter $D$ but where
the distance between the propellers can be turned continuously and where the
inertia from the pro- pellers can also be changed using different gears. No
change on the dynamics is observed when the momentum of inertia is modified.
Some dramatic changes of the shear layer position are observed modifying the
aspect ratio $\Gamma=H/D$. A bifurcation of the shear layer position appears.
Whereas for low $\Gamma$ the shear layer position has a smooth evolution when
turning the asymmetry between the rotation frequency of the propellers, for
high $\Gamma$ the transition becomes abrupt and a symmetry breaking appears.
Secondly we observe that the spontaneous reversals already observed in this ex-
periment for $\Gamma=1$ [de la Torre & Burguete PRL 99, 054101 (2007)] exist
only in a strait window of aspect ratio. We show using an experimental study of
the mean flow structure and a numerical approach based on a Langevin equation
with coloured noise that the shear layer position seems to be decided by the
mean flow structure whereas the reversals are linked to the spatial
distribution of the turbulent fluctuations in the cell.

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The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
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The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
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The categories of this paper are: q-bio
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th