Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Asymptotic turbulent friction in 2D rough-walled flows   The friction f is the property of wall-bounded flows that sets the pumping
cost of a pipeline, the draining capacity of a river, and other variables of
practical relevance. For highly turbulent rough-walled pipe flows, f depends
solely on the roughness length scale r, and the f -- r relation may be
expressed by the Strickler empirical scaling f $\propto$ r$^{\frac{1}{3}}$.
Here, we show experimentally that for soap film flows that are the
two-dimensional (2D) equivalent of highly turbulent rough-walled pipe flows, f
$\propto$ r and the f -- r relation is not the same in 2D as in 3D. Our
findings are beyond the purview of the standard theory of friction but
consistent with a competing theory in which f is linked to the turbulent
spectrum via the spectral exponent $\alpha$: In 3D, $\alpha$ = 5/3 and the
theory yields f $\propto$ r$^{\frac{1}{3}}$; in 2D, $\alpha$ = 3 and the theory
yields f $\propto$ r.

27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an