Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rheology of dense granular flows in two dimensions: Comparison of fully
  two-dimensional flows to unidirectional shear flow   This work utilizes soft-particle discrete element simulations to examine the
rheology of steady two-dimensional granular flows with reference to a
unidirectional shear flow, which has been extensively employed for validating
the local visco-plastic model of Jop et al. [Nature 441, 727--730 (2006)]. The
$\mu$-$I$ scaling proposed by Jop et al. is found to be valid in both
two-dimensional and unidirectional flows, as observed in previous studies,
however, each flow type results in a different curve. Here $\mu$, ratio of the
shear stress magnitude to the pressure, is the friction coefficient and $I$ is
the dimensionless inertial number, which is proportional to the ratio of the
magnitude of the rate of strain tensor, $\dot{\gamma}$, to the square root of
the pressure. The friction coefficient is found not to scale in a simple way
with the flow classification parameter $\psi$, which characterizes the local
flow type. All the data collapse to a single curve using the scaling proposed
by Zhang and Kamrin [Phys. Rev. Lett. 118, 058001 (2017)], in which the scaled
granular fluidity ($f=1/(\mu T)$, where $T \propto u/\dot{\gamma}$ and $u$ is
the fluctuation velocity) is found to depend only on the solid fraction $\phi$.
The data for variation of $\phi$ with inertial number $I$ collapse to a single
curve for all the flows.

3
The categories of this paper are: physics
6
The categories of this paper are: astro-ph
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg