(481b) Rheological Complexity in Yield-Stress Fluids

Fluids exhibiting a yield stress are ubiquitous in applications, and they have been studied for a hundred years, but typically in simple shear experiments where the focus has been on the dependence of the shear stress on the shear rate. In fact, even the simplest of these materials, those for which a shear sweep exhibits no hysteresis, are rheologically far more complex than is generally appreciated: they are viscoelastic both before and after yielding, as evidenced by oscillatory shear and normal stress measurements. We will explore this rheological behavior and its consequences for processing.