  We conduct simulations of the inner regions of protoplanetary disks (PPDs) to
investigate the effects of protostellar magnetic fields on their long-term
evolution. We use an inner boundary model that incorporates the influence of a
stellar magnetic field. The position of the inner disk is dependent on the mass
accretion rate as well as the magnetic field strength. We use this model to
study the response of a magnetically truncated inner disk to an episodic
accretion event. Additionally, we vary the protostellar magnetic field strength
and investigate the consequences of the magnetic field on the long-term
behavior of PPDs. We use the fully implicit 1+1D TAPIR code which solves the
axisymmetric hydrodynamic equations self-consistently. Our model allows us to
investigate disk dynamics close to the star and to conduct long-term evolution
simulations simultaneously and includes the radial radiation transport in the
stationary diffusion limit. We include stellar magnetic torques, the influence
of a pressure gradient, and a variable inner disk radius in the TAPIR code to
describe the innermost disk region in a more self-consistent manner and can
show that this approach alters the disk dynamics considerably compared to a
simplified diffusive evolution equation, especially during outbursts. The
influences of a prescribed stellar magnetic field, local pressure gradients,
and a variable inner disk radius result in a more consistent description of the
gas dynamics in the innermost regions of PPDs. Combining magnetic torques
acting on the innermost disk regions with the long-term evolution of PPDs
yields previously unseen results, whereby the whole disk structure is affected
over its entire lifetime. Additionally, we want to emphasize that a combination
of our 1+1D model with more sophisticated multi-dimensional codes could improve
the understanding of PPDs even further.
