Numerical Investigation of Particle Chain Settling in a Channel for Non-Newtonian Fluids Using the Fictitious Domain Method

Particulate flows are important in the delivery of drugs, the sedimentation of rivers, and the management of concrete. The rheological properties of fluids have a significant influence on the settling behavior of particles in these flows. The behavior of particles in flowing and sedimenting systems of chained aggregates, particularly in the context of shear-thinning, shear-thickening, and yield stress fluid rheology, is still insufficiently understood. The present study seeks to determine the effects of the rheological properties of a power-law fluid on dynamics of chain-structured circular particles in a fluid of rheological indices n = 0.9, $$n = 1.0,$$ and $$1.1$$ . A computational approach is used to study the interaction of particles with an incompressible fluid system using the Eulerian technique and the fictitious domain method (FDM). The direct volume integral method is used to compute the hydrodynamic forces of the system with a collision model for particle-particle interactions. The open-source FEATFLOW application utilizes the multigrid finite element method to structure the spatial domain, offering flexibility in simulating both fluid and particle configurations. The study illustrates how the power-law index provides varying dominant particle dynamics in various configurations of the system. For instance, shear-thinning fluids $$\\left( {n = 0.9} \\right)$$ provide flexible control of the particles, while shear-thickening fluids $$\\left( {n = 1.1} \\right)$$ impose rigid control of the particles. The rheological properties greatly influence chain formations of settling particles. Shear-thinning fluids enhance the rapid sedimentation of particles, while shear-thickening fluids induce slower and more stable configurations during sedimentation. The collision times and particle displacement were observed to vary with fluid rheology, with shear-thickening fluids demonstrating increased interparticle interactions and less particle displacement.