  We present an implicit numerical method to solve the time-dependent equations
of radiation hydrodynamics (RHD) in axial symmetry assuming hydrostatic
equilibrium perpendicular to the equatorial plane (1+1D) of a gaseous disk. The
equations are formulated in conservative form on an adaptive grid and the
corresponding fluxes are calculated by a spacial second order advection scheme.
Self-gravity of the disk is included by solving the Possion equation. We test
the resulting numerical method through comparison with a simplified analytical
solution as well as through the long term viscous evolution of protoplanetary
disk when due to viscosity matter is transported towards the central host star
and the disk depletes. The importance of the inner boundary conditions on the
structural behaviour of disks is demonstrated with several examples.
