  This paper presents a fully three-dimensional radiative hydrodymanics
simulation with realistic opacities for a gravitationally unstable 0.07 Msun
disk around a 0.5 Msun star. We address the following aspects of disk
evolution: the strength of gravitational instabilities under realistic cooling,
mass transport in the disk that arises from GIs, comparisons between the
gravitational and Reynolds stresses measured in the disk and those expected in
an alpha-disk, and comparisons between the SED derived for the disk and SEDs
derived from observationally determined parameters. The mass transport in this
disk is dominated by global modes, and the cooling times are too long to permit
fragmentation for all radii. Moreover, our results suggest a plausible
explanation for the FU Ori outburst phenomenon.
