Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Resolution requirements for simulating gravitational fragmentation using
  SPH   Jeans showed analytically that, in an infinite uniform-density isothermal
gas, plane-wave perturbations collapse to dense sheets if their wavelength,
$\lambda$, satisfies $\lambda > \lambda_{_{\rm JEANS}} = (\pi a^2 / G
\rho_{_0})^{1/2}$ (where $a$ is the isothermal sound speed and $\rho_{_0}$ is
the unperturbed density); in contrast, perturbations with smaller $\lambda$
oscillate about the uniform density state. Here we show that Smoothed Particle
Hydrodynamics reproduces these results well, even when the diameters of the SPH
particles are twice the wavelength of the perturbation. Our simulations are
performed in 3-D with initially settled (i.e. non-crystalline) distributions of
particles. Therefore there exists the seed noise for artificial fragmentation,
but it does not occur. We conclude that, although there may be -- as with any
numerical scheme -- `skeletons in the SPH cupboard', a propensity to fragment
artificially is evidently not one of them.

24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
18
The categories of this paper are: econ
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con