Structure formation in moderately concentrated viscoelastic suspensions in simple shear flow

We report experimental results on the evolution of the particle microstructure for noncolloidal particles that are suspended in a viscoelastic medium. For dilute suspensions consisting of particles having a monodisperse particle size distribution subjected to steady and oscillatory shear flows, as well as suspensions having a bidisperse size distribution subjected to steady shear, we verify previous results reported in the research literature. We also present new results of the particle microstructure for a dilute bidisperse system that was subjected to oscillatory shear. For moderately concentrated suspensions we report the formation of particle strings that correspond to a quantitative reduction in the simultaneously measured shear stress.