Triggers and signatures of shear banding in steady and time-dependent flows

• Published in: Journal of rheology (New York : 1978) Vol. 60; no. 5; pp. 821 - 834
• Main Author: Fielding, Suzanne M.
• Format: Journal Article
• Language: English
• Published: 01.09.2016
• Subjects: Flow instability; Shear banding; Extensional necking
• ISSN: 0148-6055; 1520-8516
• DOI: 10.1122/1.4961480

This précis is aimed as a practical field guide to situations in which shear banding might be expected in complex fluids subject to an applied shear flow. Separately for several of the most common flow protocols, it summarizes the characteristic signatures in the measured bulk rheological signals that suggest the presence of banding in the underlying flow field. It does so both for a steady applied shear flow and for the time-dependent protocols of shear startup, step stress, finite strain ramp, and large amplitude oscillatory shear. An important message is that banding might arise rather widely in flows with a strong enough time dependence, even in fluids that do not support banding in a steadily applied shear flow. This suggests caution in comparing experimental data with theoretical calculations that assume a homogeneous shear flow. In a brief postlude, we also summarize criteria in similar spirit for the onset of necking in extensional filament stretching.