Dilute Non-Newtonian Particle Suspension Rheology And Microstructure

The study of polymeric particle suspensions has been the subject of a number of past experimental and theoretical studies. However, fundamental questions about suspension rheology and shear flow-induced microstructural effects remain. First, a quasi-analytical study is presented that gives the first theory-based predictions on the effects of finite polymer relaxation time on rheological properties. In a constant viscosity, low polymer concentration fluid, the addition of particles is found to have a strong shear thickening effect on the first normal stress difference coefficient and the shear viscosity. In contrast, the second normal stress difference coefficient is shear thickening at low shear but shear thinning at higher shear. Next, an analytical and computational study is presented that sheds light on the widely studied phenomenon of cross-streamline particle migration in Poiseuille flow. Particles are found to experience a cross-stream force toward the channel center when they are freely suspended in the fluid, while they experience a crossstream force toward the wall when they are fixed in place