  We study a self-similar circulation model for protostellar bipolar outflows.
The model is axisymmetric and stationary, and now includes Poynting flux.
Compared to an earlier version of the model, this addition produces faster and
more collimated outflows. Moreover the luminosity needed for the radiative
heating is smaller. The model has been applied to both low and high mass
protostars. Monte Carlo methods have been used to explore systematically the
parameter space. An inflow/outflow pattern including collimation of high speed
material and an infalling toroidal disc arises naturally. The disc shape
depends on the imposed heating, but it is naturally Keplerian given the central
point mass. Outflows can have large opening angles, that increase when magnetic
field weakens. Massive protostars produce faster but less collimated outflows
than less massive protostars. The model is now at a stage where synthetic CO
spectra reproduce very well the observational features. The results strengthen
the idea that radiative heating and Poynting flux are ultimately the energy
sources driving the outflow.
