Rheological instability in a simple shear-thickening model
Department of Physics and Astronomy, JCMB King's Buildings
University of Edinburgh, Edinburgh EH9 3JZ, UK
2 Laboratoire de Physico-Chimie Théorique, Esa CNRS 7083, ESPCI 10 rue Vauquelin, F-75231 Paris Cedex 05, France
Accepted: 15 October 2001
We study the strain response to steady imposed stress in a spatially homogeneous, scalar model for shear thickening, in which the local rate of yielding of mesoscopic “elastic elements” is not monotonic in the local strain l. Despite this, the macroscopic, steady-state flow curve (stress vs. strain rate) is monotonic. However, for a broad class of , the response to steady stress is not in fact steady flow, but spontaneous oscillation. We discuss this finding in relation to other theoretical and experimental flow instabilities. Within the parameter ranges we studied, the model does not exhibit rheo-chaos.
PACS: 83.60.Rs – Shear rate-dependent structure (shear thinning and shear thickening) / 83.60.Wc – Flow instabilities / 82.40.Bj – Oscillations, chaos, and bifurcations
© EDP Sciences, 2002