Rheology of viscoelastic suspensions

The rheology of suspensions of solid particles in viscoelastic fluids is important in many technological applicatoins as exemplified by the processinf of filled polymers. Consequently, considerable attentions in the literature is given to the rheology of suspesnions fo particles. Most studies are focused on highly filled systems with polydisperse partciles of irregular shapes. In contrat, few studies are conducted ont he rheology of dilute and semi-dilute suspensions of monodisperse spheres. We elucidate the effect of viscoelasticity ont he bulk rheological properties. The hehaviour of model suspensions composed of non Bronwnian rigid spehres immmersed in Newtonian and viscoelastic matrices is investigated in the concentration range from 0 up to 10%. In parallel with the experiments, new simultaion techniques for suspesnions in Newtonian fluids under oscillatory shear flow is presented. The case of a single sphere and two particels are studied and discussed. The flow induced microstructure of suspensions in viscoelastic fluids is studied by rheo-optical techiniques. More specifically,the flow-induced alignment of non-colloidal particles in viscoelastic fluiids is investigated systematically in an attempt to quantify the alignment of the particles and correlate it with the shear rate, size aof the particles and interactions with the wall.