Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Description of laminar-turbulent transition of an airfoil boundary layer
  measured by differential image thermography using directed percolation theory   Transition from laminar to turbulent flow is still a challenging problem.
Recent studies indicate a good agreement when describing this phase transition
with the directed percolation theory. This study presents a new experimental
approach by means of differential image thermography (DIT) enabling to
investigate this transition on the suction side of a heated airfoil. The
results extend the applicability of the directed percolation theory to describe
the transition on curves surfaces.
  The experimental effort allows for the first time an agreement between all
three universal exponents of the (1+1)D directed percolation for such airfoil
application. Furthermore, this study proves that the theory holds for a wide
range of flows, as shown by the various conditions tested. Such a large
parameter space was not covered in any examination so far. The findings
underline the significance of percolation models in fluid mechanics and show
that this theory can be used as a high precision tool for the problem of
transition to turbulence.

4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
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The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th