This book contributes to the fundamental understanding of the physical mechanisms that take
place in pseudo turbulent particulate flows. In the present work we have considered the
sedimentation of large numbers of spherical rigid particles in an initially quiescent flow
field. We have performed direct numerical simulations employing an immersed boundary method for
the representation of the fluid-solid interface. The results evidence that depending on the
particle settling regime (i.e. Galileo number and particle-to-fluid density ratio) the
particles may exhibit strong inhomogeneous spatial distribution. It is found that the particles
are preferentially located in regions with downward fluid motion. The particles inside clusters
experience larger settling velocities than the average. The flow in all flow cases is observed
to exhibit characteristic features of pseudo-turbulence. The particle-induced flow field is
further found to be highly anisotropic with dominant vertical components. The results indicate
that in the present flow configurations the collective and mobility effects play significant
role for the particle and fluid motion.
