Structure Formation of Non-Colloidal Particles in Viscoelastic Fluids Subjected to Simple Shear Flow

The alignment and the aggregation of particles in a viscoelastic fluid in simple shear flow are qualitatively analyzed using a two-dimensional direct numerical simulation. Depending on the shear thinning, solvent viscosity, and Weissenburg number, a typical sequence in structural transitions from random particle configuration to string formation is found with clustering and clustered string formation in between. The solvent viscosity and the Weissenburg number, the ratio of normal stress to shear stress, are found to be the most influential parameters for the onset of string formation. The influence of shear thinning is less clear. More shear thinning seems to promote string formation if the stress ratio is constant. The angular velocity of the particles is reduced by approximately 60% when particles form a string, independent of the parameters used.