Pair-particle trajectories in Bingham shear flow
Abstract
Using numerical simulations we discuss the hydrodynamic interactions of two particles suspended in a Bingham fluid subjected to linear shear flow. The computations are based on the fictitious domain method with distributed Lagrange multipliers. Most of our simulations are for two equal radii cylinders in two dimensions but some examples are given for two spheres in three dimensions. Fluid and particle inertia are not taken into account (Re=0). Three different contact models (smooth particles, Glowinsky model and Cunha-Hinch model) have been implemented. We calculate the change between the initial and final streamlines caused by roughness as a function of the initial separation of the particles, the Bingham number and the roughness size. We put into evidence that Bingham number has a strong impact on the asymmetry of the trajectories: larger the Bingham number larger the net displacement across streamlines caused by a collision. We also show that Glowinky and Cunha-Hinch roughness models have similar effect on the collision for well chosen Glowinski model's parameters. To conclude shear-induced microstructure in non-Brownian dilute suspensions of rough particles is computed which allows to determine the pair distribution function.