Paper Number
NF14 

Session
Non-Newtonian Fluid Mechanics & Instabilities

Title
Stability of shear banded flow for a viscoelastic constitutive model with thixotropic yield stress behavior

Presentation Date and Time
February 15, 2017 (Wednesday) 2:45

Track / Room
Track 2 / Audubon A

Authors (Click on name to view author profile)

1. Renardy, Yuriko (Virginia Tech, Department of Mathematics)
2. Renardy, Michael (Virginia Tech, Department of Mathematics)

Author and Affiliation Lines (in printed abstract book)
Yuriko Renardy and Michael Renardy
Department of Mathematics, Virginia Tech, Blacksburg, VA 24061

Speaker / Presenter 
Renardy, Yuriko

Text of Abstract
We examine the stability of two-layer shear flow, one layer yielded and the other unyielded, for a PECN fluid. The PECN model is a viscoelastic constitutive model which combines the partially extending strand convection model (PEC) with a Newtonian solvent. We define ε to be the ratio of retardation time to relaxation time and focus on the case of small ε. A linear stability analysis is conducted of shear banded flows, and the interface is found to be unstable. The instability is driven by a normal stress difference across the interface. As for the Johnson-Segalman model, which has been studied in earlier literature, the PEC model has a higher normal stress in the high shear rate phase than in the low shear rate phase. To assess the importance of this property, we also investigate a model which is specifically designed to reverse this. It is found that instabilities still occur, although the range of unstable wave numbers is reduced.