  We study the axisymmetric and non-axisymmetric, time-dependent hydrodynamics
of gas that is under the influence of the gravity of a super massive black hole
(SMBH) and the radiation force produced by a radiatively efficient flow
accreting onto the SMBH. We have considered two cases: (1) the formation of an
outflow from the accretion of the ambient gas without rotation and (2) that
with weak rotation. The main goals of this study are: (1) to examine if there
is a significant difference between the models with identical initial and
boundary conditions but in different dimensionality (2-D and 3-D), and (2) to
understand the gas dynamics in AGN. Our 3-D simulations of a non-rotating gas
show small yet noticeable non-axisymmetric small-scale features inside the
outflow. The outflow as a whole and the inflow do not seem to suffer from any
large-scale instability. In the rotating case, the non-axisymmetric features
are very prominent, especially in the outflow which consists of many cold dense
clouds entrained in a smoother hot flow. The 3-D outflow is non-axisymmetric
due to the shear and thermal instabilities. In both 2-D and 3-D simulations,
gas rotation increases the outflow thermal energy flux, but reduces the outflow
mass and kinetic energy fluxes. Rotation also leads to time variability and
fragmentation of the outflow in the radial and latitudinal directions. The
collimation of the outflow is reduced in the models with gas rotation. The time
variability in the mass and energy fluxes is reduced in the 3-D case because of
the outflow fragmentation in the azimuthal direction. The virial mass estimated
from the kinematics of the dense cold clouds found in our 3-D simulations of
rotating gas underestimates the actual mass used in the simulations by about 40
%. (Abbreviated)
