  We study the time evolution of sub-Keplerian transonic accretion flow onto a
non-rotating black hole using a three-dimensional, inviscid hydrodynamics
simulation code. Prior two-dimensional simulations show that centrifugal
barrier in the accreting matter may temporarily halt the nearly free-falling
matter and produce a stable, geometrically thick disk which may contain
turbulent eddies. Our goal in this work is to investigate whether the disk
develops any instability because of this turbulence when we dynamically
activate all three dimensions. We find that the disk remains stable and
axisymmetric even close to the central black hole. However, if we explicitly
apply non-axisymmetric azimuthal perturbation, the axisymmetric structure of
the disk is destroyed and instability is developed.
