Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A scale-wise analysis of intermittent momentum transport in dense canopy
  flows   We investigate the intermittent dynamics of momentum transport and its
underlying time scales in the near-wall region of the neutrally stratified
atmospheric boundary layer in the presence of a vegetation canopy. This is
achieved through persistence analysis, namely the probability that turbulent
velocity fluctuations do not change sign up to some time, and their connection
to the ejection-sweep cycle. Using high-frequency field measurements spanning
multiple heights within and above a dense canopy, the analysis suggests that
when the persistence time scales associated with ejections and sweeps are
normalized by $u_*$ and $h$ (friction velocity at the canopy top and canopy
height), their distributions are height-invariant and also markedly different
from a randomly-shuffled configuration. These results point to the persistent
memory imposed by canopy-induced coherent structures, and to their role as an
efficient momentum transport mechanism between the canopy airspace and the
region immediately above. Moreover, these distributions exhibit a power-law
scaling at short times ($<0.1h/u_*$), followed by an exponential tail at longer
times, with the cut-off scale being commensurate with the integral time scale
of the vertical velocity. Quadrant analysis reveals that intense sweeping
motions dominate the power law behavior, while low-amplitude ejections are the
prominent features of the long-lived events. By employing surrogate data, we
establish that at short times the non-local nature of momentum transport is
caused by amplitude variability rather than zero-crossing properties, providing
then an original explanation to the known role of sweeping motion in violating
gradient diffusion (K-theory) models in canopy turbulence.

25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex