  We present hydrodynamic simulations of the common envelope binary interaction
between a giant star and a compact companion carried out with the adaptive mesh
refinement code ENZO and the smooth particle hydrodynamics code PHANTOM. These
simulations mimic the parameters of one of the simulations by Passy et al., but
assess the impact of a larger, more realistic initial orbital separation on the
simulation outcome. We conclude that for both codes the post-common envelope
separation is somewhat larger and the amount of unbound mass slightly greater
when the initial separation is wide enough that the giant does not yet overflow
or just overflows its Roche lobe. PHANTOM has been adapted to the common
envelope problem here for the first time and a full comparison with ENZO is
presented, including an investigation of convergence as well as energy and
angular momentum conservation. We also set our simulations in the context of
past simulations. This comparison reveals that it is the expansion of the giant
before rapid in-spiral and not spinning up of the star that causes a larger
final separation. We also suggest that the large range in unbound mass for
different simulations is difficult to explain and may have something to do with
simulations that are not fully converged.

Solar and Stellar Astrophysics