Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bulldozing of granular material   We investigate the bulldozing motion of a granular sandpile driven forwards
by a vertical plate. The problem is set up in the laboratory by emplacing the
pile on a table rotating underneath a stationary plate; the continual
circulation of the bulldozed material allows the dynamics to be explored over
relatively long times, and the variation of the velocity with radius permits
one to explore the dependence on bulldozing speed within a single experiment.
We measure the time-dependent surface shape of the dune for a range of rotation
rates, initial volumes and radial positions, for four granular materials,
ranging from glass spheres to irregularly shaped sand. The evolution of the
dune can be separated into two phases: a rapid initial adjustment to a state of
quasi-steady avalanching perpendicular to the blade, followed by a much slower
phase of lateral spreading and radial migration. The quasi-steady avalanching
sets up a well-defined perpendicular profile with a nearly constant slope. This
profile can be scaled by the depth against the bulldozer to collapse data from
different times, radial positions and experiments onto common master curves
that are characteristic of the granular material and depend on the local Froude
number. The lateral profile of the dune along the face of the bulldozer varies
more gradually with radial position, and evolves by slow lateral spreading. The
spreading is asymmetrical, with the inward progress of the dune eventually
arrested and its bulk migrating to larger radii. A one-dimensional
depth-averaged model recovers the nearly linear perpendicular profile of the
dune, but does not capture the finer nonlinear details of the master curves. A
two-dimensional version of the model leads to an advection-diffusion equation
that reproduces the lateral spreading and radial migration.

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The categories of this paper are: astro-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: stat
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The categories of this paper are: nlin
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: bayes-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: cs