  We perform controlled N-Body/SPH simulations of disk galaxy formation by
cooling a rotating gaseous mass distribution inside equilibrium cuspy spherical
and triaxial dark matter halos. We systematically study the angular momentum
transport and the disk morphology as we increase the number of dark matter and
gas particles from 10^4 to 10^6, and decrease the gravitational softening from
2 kpc to 50 parsecs. The angular momentum transport, disk morphology and radial
profiles depend sensitively on force and mass resolution. At low resolution,
similar to that used in most current cosmological simulations, the cold gas
component has lost half of its initial angular momentum via different
mechanisms. The angular momentum is transferred primarily to the hot halo
component, by resolution-dependent hydrodynamical and gravitational torques,
the latter arising from asymmetries in the mass distribution. In addition,
disk-particles can lose angular momentum while they are still in the hot phase
by artificial viscosity. In the central disk, particles can transfer away over
99% of their initial angular momentum due to spiral structure and/or the
presence of a central bar. The strength of this transport also depends on force
and mass resolution - large softening will suppress the bar instability, low
mass resolution enhances the spiral structure. This complex interplay between
resolution and angular momentum transfer highlights the complexity of
simulations of galaxy formation even in isolated haloes. With 10^6 gas and dark
matter particles, disk particles lose only 10-20% of their original angular
momentum, yet we are unable to produce pure exponential profiles.
