Fall 2014
Colloquia are held on Fridays at 11:30 a.m. in Cullimore Lecture Hall II, unless noted otherwise. Refreshments are served at 11:30 am. For questions about the seminar schedule, please contact Yassine Boubendir.
Date: October 10, 2014
Speaker: Yuriko Renardy
Department of Mathematics,
Virginia Polytechnic Institute and State University
Title: "A Viscoelastic Constitutive Model That Predicts Thixotropic Yield Stress Behavior for Large Relaxation Time"
Abstract:
This talk will be on the predictions of a constitutive model which combines the partially extending strand convection model for an entangled microstructure, with a Newtonian solvent. There are two time scales, a long one associated with the relaxation time of the microstructure, and a short one for the solvent. A class of initial value problems driven by an initially applied stress is examined with numerical computations, which show complicated transients for yielding to flow and unyielding back to a solid state. These transients are captured by asymptotic methods based on the multiple time scales, in the limit of large relaxation time. The case of an initial shear stress jump and subsequent homogeneous parallel shear flow is found to give a mathematical perspective on ketchup (joint work with Kara Maki, RIT). In recent work with Holly Grant (Virginia Tech), we examine idealized 3D extensional flow, as initial value problems with prescribed tensile stress. As time permits, the more realistic example of a model for a filament in extension will be described.