Elasto-inertial particle migration in a confined simple shear-flow of Giesekus viscoelastic fluids

Abstract

Particle migration and trajectory patterns in a confined simple shear-flow of Giesekus viscoelastic fluid are studied numerically using the direct forcing/fictitious domain method with Reynolds number, Re, from 0.1 to 50, Weissenberg number, Wi, from 0.1 to 1.0, and ratio of solvent viscosity to total viscosity at 0.3. The method is validated by comparing the present results with previous numerical results and experimental data. The effects of fluid inertia and elasticity, wall confinement, and initial horizontal distance between two particles on particle migration and trajectory pattern are analyzed. The results show that there exist two trajectory patterns, that is, “returning” and “passing” patterns. The separatrix between the two patterns and the velocity variation of particles are dependent on Re and h (initial vertical distance between the two particles). The elastic effect promotes a change in particle trajectory from the returning to the passing pattern when the elasticity number is large, while the inertial effect promotes a change in particle trajectory from the passing to the returning pattern. A large extension force causes the two particles to pass over each other. Wall confinement promotes a change in particle trajectory from the passing to the returning pattern. The initial horizontal distance, l, between two particles has no effect on the trajectory pattern when the inertial effect is small. The larger l is, the more likely it is that the returning pattern appears. The particle trajectories are closer to the centerline when l is large.