Binary interactions of stochastically rough, charged spheres in planar Couette and Poiseuille flow

摘要

Numerical simulations are performed using a semi-analytic method to study the interactions of two neutrally buoyant, stochastically rough spheres that are subjected to repulsive and attractive static forces in planar Couette and Poiseuille Stokes flow. Both particle roughness and static force introduce irreversibility into these systems resulting in asymmetries in the particle trajectories. These asymmetries lead to particle dispersion and migration. It has previously been shown that particle pairs migrate toward the low shear rate region of the flow field for neutrally charged rough spheres. Applying an attractive static force to the rough particles reduces the particle dispersion while applying a repulsive static force increases the particle dispersion. Increasing the attractive force between the two rough spheres decreases the net particle migration to the extent that the particle pairs may actually migrate toward the high shear rate region of the flow. As the nonlinearity of the flow field increases, the average dispersion increases with repulsive forces, decreases with attractive forces, and remains essentially constant for neutrally charged spheres. The effect of standard deviation of particle roughness on in-plane particle dispersion and net particle migration is investigated. (C) 2018 The Society of Rheology.