Molecular outflows are believed to be an essential mechanism in the star
formation process where they facilitate the collapse of a pre-stellar
core into star by acting as a channel to remove an excess of
angular momentum from the system. The outflows develop into massive
extended structures hundreds of light years in length, and which evolve
over timescales of tens of thousands of years. They may even be a source
of turbulence in molecular clouds which helps regulate the star
formation rate.

We performed an investigation, via numerical simulations, of the
properties of bipolar outflows and how they are effected by both the
underlying jet beam and the surrounding ambient environment.
Mass-velocity distributions were plotted in order to link the
simulations to observations.

Firstly we focused on simulating jets of various velocities and
compositions, obtaining shallow mass-spectra (~1-2) which were
independent of jet velocity, but found that steeper mass-spectra could
be achieved through an atomic-jet/molecular-medium combination.
Next we turned to the ambient environment and created realistic
protostellar environments consisting of density gradients and density
discontinuities. We found that a non-uniform medium lead to steeper
mass-spectra, in line with those obtained from observations, and that
the mass-spectrum of an outflow can vary substantially during its
dynamical evolution.