We use a virtual Couette rheometer to study the behaviour of dry and wet
granular materials in aerated bed. A typical fluidization curve for dry
powders exhibits fixed bed characterized by linear increase in pressure
drop with increasing air velocity. This is followed by a fluidized bed
at a constant pressure drop with further increase in air velocity.
However, wet powders display different aeration behaviour due to the
inhomogeneous gas flow through the bed. The fluidization behaviour of
the powder upon addition of small amounts of silicon oil liquid has been
tested for two different grain sizes. We distinguish different regimes
of fluidization for wet powders with different saturation of silicon oil
and different grain sizes. Further, we compare the hysteresis effects in
fluidization and de-fluidization cycles of the materials. We also
compare the shear stresses and study the rheology of the materials under
different fluidized condition.