  Fluidisation is the process by which the weight of a bed of particles is
supported by a gas flow passing through it from below. When fluidised materials
flow down an incline, the dynamics of the motion differ from their
non-fluidised counterparts because the granular agitation is no longer required
to support the weight of the flowing layer. Instead, the weight is borne by the
imposed gas flow and this leads to a greatly increased flow mobility. In this
paper, a framework is developed to model this two phase motion by incorporating
a kinetic theory description for the particulate stresses generated by the
flow. In addition to calculating numerical solutions for fully developed flows,
it is shown that for sufficiently thick flows there is often a local balance
between the production and dissipation of the granular temperature. This
phenomenon permits an asymptotic reduction of the full governing equations and
the identification of a simple state in which the volume fraction of the flow
is uniform. The results of the model are compared with new experimental
measurements of the internal velocity profiles of steady granular flows down
slopes. The distance covered with time by unsteady granular flows down slopes
and along horizontal surfaces and their shapes are also measured and compared
with theoretical predictions developed for flows that are thin relative to
their streamwise extent. For the horizontal flows, it was found that resistance
from the sidewalls was required in addition to basal resistance to capture
accurately the unsteady evolution of the front position and the depth of the
current and for situations in which side-wall drag dominates, similarity
solutions are found for the experimentally-measured motion.
