The flow of suspensions through tubes.

The flow mechanism of concentrated suspensions of rigid particles undergoing slow Poiseuille flow was studied. It was shown that the deviations tram the parabolic velocity distribution arise from a wall effect of the type described by Vand. Particle accumulation behind an advancing meniscus is caused by the radial flow and particle-particle and particle-wall interactions. In many cases, the motions of particles were reversible when the direction of flow vas reversed. In dilute suspensions, the statistical properties of the particle paths were in good agreement with a theory of collision doublets based on reotilinear paths of approach and recession. [...