(98j) Shear-Induced Ordering and Aggregation in Dense Soft Particle Suspensions

The flow of dense soft particulate suspensions is ubiquitous in food processing and blood flow. We investigate the effect of particle aggregation and shear-induced ordering on suspension properties with multi-scale computational models.  Under shear, dense particles suspension (> 65% packing) with amorphous structure may be driven to crystalline packing.  In addition, particle deformation under shear forces leads to anisotropic structure, which confirms previous experimental observations.  In dense suspensions, non-Newtonian dynamics of a mono-disperse soft particle suspensions may be due to the change in the inter- and intra-particle structure under flow.  We closely examined the coupling between flow and particle aggregation. Flow is found to both enhance and hinder particle aggregate and cluster-formation depending on the shear force, particle elasticity, particle shape, and inter-particle attraction. Depending on the average aggregate size and particle deformation under shear, the non-linear dependence of suspension viscosity on the shear rate is characterized and found to agree with prior measurements of blood rheology.  The computational model is capable of predicting particulate suspension rheology given parameter-engineered particles.