  We use numerical simulations of turbulent cluster-forming regions to study
the nature of dense filamentary structures in star formation. Using four
hydrodynamic and magnetohydrodynamic simulations chosen to match observations,
we identify filaments in the resulting column density maps and analyze their
properties. We calculate the radial column density profiles of the filaments
every 0.05 Myr and fit the profiles with the modified isothermal and pressure
confined isothermal cylinder models, finding reasonable fits for either model.
The filaments formed in the simulations have similar radial column density
profiles to those observed. Magnetic fields provide additional pressure support
to the filaments, making `puffier' filaments less prone to fragmentation than
in the pure hydrodynamic case, which continue to condense at a slower rate. In
the higher density simulations, the filaments grow faster through the increased
importance of gravity. Not all of the filaments identified in the simulations
will evolve to form stars: some expand and disperse. Given these different
filament evolutionary paths, the trends in bulk filament width as a function of
time, magnetic field strength, or density, are weak, and all cases are
reasonably consistent with the finding of a constant filament width in
different star-forming regions. In the simulations, the mean FWHM lies between
0.06 and 0.26 pc for all times and initial conditions, with most lying between
0.1 to 0.15 pc; the range in FWHMs are, however, larger than seen in typical
Herschel analyses. Finally, the filaments display a wealth of substructure
similar to the recent discovery of filament bundles in Taurus.

Astrophysics of Galaxies;Solar and Stellar Astrophysics