Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Radial segregation driven by axial convection   We experimentally study the mixing of binary granular systems in a horizontal
rotating cylinder. When materials have the same size and differ by dynamic
angle of repose only, we observe an axial transport of matter that generates
transient radial segregation. The system then evolves towards homogeneity. If
materials differ by density also radial segregation becomes steady. A mechanism
is suggested where radial segregation is promoted by axial differences of
dynamic angle of repose. This differs from the free surface segregation
suggested so far to explain radial segregation.

30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph