Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Detailed Model of the Growth of Fluffy Dust Aggregates in a
  Protoplanetary Disk: Effects of Nebular Conditions   Coagulation of dust aggregates plays an important role in the formation of
planets and is of key importance to the evolution of protoplanetary disks
(PPDs). Characteristics of dust, such as the diversity of particle size,
porosity, charge, and the manner in which dust couples to turbulent gas, affect
the collision outcome and the rate of dust growth. Here we present a numerical
model of the evolution of the dust population within a PPD which incorporates
all of these effects. The probability that any two particles collide depends on
the particle charge, cross-sectional area and their relative velocity. The
actual collision outcome is determined by a detailed collision model which
takes into account the aggregate morphology, trajectory, orientation, and
electrostatic forces acting between charged grains. The data obtained in this
research reveal the characteristics of dust populations in different
environments at the end of the hit-and-stick growth, which establishes the
foundation for the onset of the next growth stage where bouncing, mass transfer
and fragmentation become important. For a given level of turbulence, neutral
and weakly charged particles collide more frequently and grow faster than
highly charged particles. However, highly charged particles grow to a larger
size before reaching the bouncing barrier, and exhibit a "Runaway" growth, in
which a few large particles grow quickly by accreting smaller particles while
the rest of the population grows very slowly. In general, highly charged
aggregates have a more compact structure and are comprised of larger monomers
than neutral/weakly charged aggregates. The differences in the particle
structure/composition not only affect the threshold velocities for bouncing and
fragmentation, but also change the scattering and absorption opacity of dust,
influencing the appearance of PPDs.

30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas