  Viscous Keplerian discs become sub-Keplerian close to a black hole since they
pass through sonic points before entering into it. We study the time evolution
of polytropic viscous accretion discs (both in one and two dimensional flows)
using Smoothed Particle Hydrodynamics. We discover that for a large region of
the parameter space, when the flow viscosity parameter is less than a critical
value, standing shock waves are formed. If the viscosity is very high then the
shock disappears. In the intermediate viscosity the disc oscillates very
significantly in viscous time-scale. Our simulations indicate that these
centrifugally supported high density region close to a black hole plays an
active role in the flow dynamics, and consequently, the radiation dynamics.
