Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Influence of grain bidispersity on dense granular flow in a two
  dimensional hopper   Discrete element method is conducted to investigate the bidisperse dense
granular flow having big and small grains in a two dimensional hopper. A
half-circular dynamical force arch is observed above the outlet and Beverloo's
law is verified to describe the relationship between flow rate and outlet size.
The bidisperse flow can reach the maximum flow rate when a small fraction of
big grains is added into the monodisperse flow with only small grains. The
distributions of contact force, packing fraction and grain velocity indicate
that the flow properties in the hopper are closely related to the local flow
characteristics of the key area which almost overlaps with the force arch. The
interior packing structures, i.e., ordered arrangement for monodisperse flow
and disordered arrangement for bidisperse flow, play a dominant role in the
flow pattern transition from mass flow to funnel flow. The earlier occurrence
of the transition can effectively increase the grain velocity and therefore
improve the flow rate.

17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs