Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Turbulence induced collisional velocities and density enhancements:
  large inertial range results from shell models   To understand the earliest stages of planet formation, it is crucial to be
able to predict the rate and the outcome of dust grains collisions, be it
sticking and growth, bouncing, or fragmentation. The outcome of such collisions
depends on the collision speed, so we need a solid understanding of the rate
and velocity distribution of turbulence-induced dust grain collisions. The rate
of the collisions depends both on the speed of the collisions and the degree of
clustering experienced by the dust grains, which is a known outcome of
turbulence. We evolve the motion of dust grains in simulated turbulence, an
approach that allows a large turbulent inertial range making it possible to
investigate the effect of turbulence on meso-scale grains (millimeter and
centimeter). We find three populations of dust grains: one highly clustered,
cold and collisionless; one warm; and the third "hot". Our results can be fit
by a simple formula, and predict both significantly slower typical collisional
velocities for a given turbulent strength than previously considered, and
modest effective clustering of the collisional populations, easing difficulties
associated with bouncing and fragmentation barriers to dust grain growth.
Nonetheless, the rate of high velocity collisions falls off merely
exponentially with relative velocity so some mid- or high-velocity collisions
will still occur, promising some fragmentation.

18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
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The categories of this paper are: eess
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
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The categories of this paper are: math-ph
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The categories of this paper are: quant-ph
1
The categories of this paper are: cs