| Scope and method of study. This study examines concentration and velocity patterns observed in a horizontal rotating cylinder completely filled with a monodisperse suspension of non-Brownian particles. Individual phases are studied and the boundaries separating adjacent patterns and their functional dependence on the particle radius, cylinder radius, and particle concentration are examined in an attempt to facilitate a theoretical understanding of the system.; Findings and conclusions. Our attempts to arrive at dimensionless control parameters have yielded preliminary but reassuring results. These parameters are derived from our current knowledge of the forces affecting the system, but do not account for particle interactions. The scaling analysis suggests that the phase diagram can be divided into three regions. In the low rotation rate region, the transition boundaries show strong particle size dependence, indicating that hydrodynamic forces resulting from the settling of individual particles are dominant. Conversely, the high rotation rate region shows negligible particle size dependence indicating that the centrifugal force is dominant. This division in the phase diagram suggests that at least two dimensionless parameters are needed to describe the phase behavior of the system. The transition boundaries in the intermediate region show more complex behavior suggesting a strong competition among the viscous, gravitational, and centrifugal forces. Understanding this seemingly simple system will shed new light to the field of suspension dynamics and provide a theoretical framework to a long forsaken and theoretically prohibitive area of hydrodynamics. |
