The flow of suspensions through tubes: V. Inertial effects

The behavior of particles undergoing Couette and Poiseuille flows at rates when inertial effects become significant was investigated. The rotation of rigid particles was similar to that in the Stokes flow regime, except for a drift of cylinders to limiting rotational orbits corresponding to the maximum energy dissipation. In Poiseuille flow, rigid particles migrated to an equilibrium radial position which depended on the density difference of two phases, the directions of sedimentation velocity and flow, and the ratio of particle to tube radius. Neutrally buoyant deformable particles always migrated to the tube axis. In concentrated suspensions a plasmatic layer developed near the tube wall as a consequence of radial migration. The formation of this layer modified the velocity profile and caused a reduction in the apparent viscosity coefficient.