Two-dimensional computational fluid dynamical investigation of particle migration in rotating eccentric cylinders using suspension balance model

•Suspension flow in an eccentric journal bearing using SBM was numerically examined.•We used COMSOL Multiphysics to investigate the two dimensional problem.•The concentration, the velocity profiles and the effect of eccentricity has been examined.•The eccentricity ratio plays an important role on the maximum concentration changes.•These simulation results agree with the experimental data of Subia et al. (1998).

Suspension balance and diffusive flux models have been developed to explain the particle migration phenomenon. Herein, we use the suspension balance model (SBM) to provide numerical validation of the particle migration in a concentrated suspension undergoing flow between rotating eccentric cylinders observed in the literatures. This study demonstrates that by implementing the mathematical model developed to explain the particle migration phenomenon, namely SBM into available commercial software such as COMSOL Multiphysics, one can readily explore the behavior of these systems. A two-dimensional finite element model of the SBM has been created in COMSOL Multiphysics. A set of transient conservation equations of bulk and particle-phase mass and momentum that included gravitational force effects were solved using the implicit time-stepping method of backward differentiation. The simulation method was validated using the available analytical solution for suspension in a circular Couette flow. The eccentricity ratio has been defined as ε = e/(Ro−Ri), where Ro is the outer cylinder radius, Ri is the inner cylinder radius and e is the distance between the center of the inner and outer cylinders. The eccentricity ratio was analyzed, and it was shown that for the eccentricity ratio, ε<0.5 and particle volume fraction, ϕ = 50%, the maximum concentration occurs along the circumference in the direction of the stationary cylinder. As ε increases and when ϕ = 50%, the maximum concentration appears along the horizontal mid-plane of the eccentric bearing in the wide-gap region. Further increases in the eccentricity ratio shift the maximum concentration region towards the rotating cylinder. The simulation results of the concentration distribution and the velocity profile compare well with the experimental data. This study provides a qualitative step forward in the application of computational fluid dynamics to suspension flows in various geometries and serves as a first step towards exploring the realistic three-dimensional modeling of dense suspensions in eccentric bearings as an example of general geometries.