Settling Dynamics of a Pair of Circular Cylinders in a Non-Newtonian Fluid

The behavior of solid cylinders in particulate flows is studied, focusing on their interactions with the surrounding fluid. Fluid dynamics are modeled using the power law model that accounts for the shear-thinning, Newtonian, and shear-thickening fluids. The fictitious boundary method (FBM) is employed to model the cylinder-fluid interactions within the Eulerian framework. The hydrodynamic forces exerted on the cylinder surfaces are calculated using the explicit volume integral technique. The findings indicate that the initial inter-cylinder distance and the Reynolds number significantly affect settling velocities of the two falling cylinders and their maximum separation distance. In shear-thinning fluids $$\left( {n = 0.9} \right)$$ , significant repulsive forces induce cylinder dispersion, especially at higher Reynolds numbers. In Newtonian fluids (n = 1), the cylinder behavior is more uniform, while in shear-thickening fluids $$\left( {n = 1.1} \right)$$ , the increased resistance reduces variations in the cylinder velocity. The innovation of this study lies in integrating the FBM using the power law model, enabling a comprehensive comparison of cylinder dynamics for various types of fluids. The study demonstrates how the fluid rheology influences sedimentation, cylinder separation, and settling velocities, emphasizing the significant impact of both fluid type and initial cylinder separation on the cylinder behavior. Numerical investigations using the FEATFLOW simulation tool provide high-resolution results for cylinder dynamics and sedimentation behavior under various fluid conditions.