Axial and radial patterns of a bidispersed suspension in a fully filled horizontal rotating cylinder

Abstract

We report on the pattern formation in a horizontal rotating cylinder fully filled with bidispersed suspension composed of non-Brownian settling and floating particles. The effect of particle mixing of different buoyancy and shape on the axial and radial pattern formation was investigated using flow visualization and particle image velocimetry techniques. The experimental investigations involved two cases divided according to the shape of the particles making up the suspension. In the first case, both the floating and settling particles were spherical in shape while the second one was composed of buoyant spherical and settling cylindrical particles. A detailed analysis of the difference between the monodispersed and bidispersed suspension for various rotational speeds is provided. The radial and axial patterns for the bidispersed suspension was found to strongly depend on the rotation rate. The behavior at low rotation was similar to that of monodispersed systems, but at higher speeds, hybrid patterns emerged that were driven by the complementary influence of the two kinds of particles. The patterns observed were seen to be primarily influenced by the particle-particle hydrodynamic interaction. The nonspherical nature of the cylindrical particles produces radial and axial patterns that are distinctly different from the spherical particles.