The effect of sphere-wall interactions on particle motion in a viscoelastic suspension of FENE dumbbells (Q1303066)

The authors examine the motion of particles in viscoelastic fluid in bounded geometry by incorporating viscoelasticity into low Reynolds number hydrodynamics, modelling viscoelasticity as suspension of finite-extension nonlinearly elastic (FENE) dumbbells. Wall-particle and wall-bead interactions are included using the image system method. The numerical study shows that a single sphere sedimenting near a wall moves towards the wall and exhibits anomalous rotation. The lateral velocity of the particle is proportional to its fall velocity, and shows the existence of a critical sphere-wall distance beyond which the attraction is negligible. The particle-wall attraction is strong enough to overcome a light tilt in the wall, but the particle moves away from the wall when it is tilted by an angle larger than a certain critical value. The sphere size has a considerable effect on the distance travelled by the sphere before reaching the wall. A nonspherical particle settling in a channel exhibits an oscillatory motion, but ultimately is oriented with its long axis parallel to gravity. A neutrally buoyant sphere in plane Poiseuille flow migrates to the channel centre in wide channels but migrates to the walls when the radius of the sphere is large compared to the channel width. The method of the paper shows promise as the computations agree with experimental observations available in the literature.