Hostname: page-component-7479d7b7d-fwgfc Total loading time: 0 Render date: 2024-07-15T21:44:51.186Z Has data issue: false hasContentIssue false

Rheological modeling of complex fluids: III. Dilatant behavior of stabilized suspensions

Published online by Cambridge University Press:  15 September 1998

D. Quemada*
Affiliation:
Laboratoire de Biorhéologie et d'Hydrodynamique Physico-chimique, Université Denis Diderot (Paris 7) (CNRS ESA 7057) LBHP, case 7056, Université Paris 7, 2 place Jussieu, 75251 Paris Cedex 05, France
Get access

Abstract

A new structural model of shear-thickening “dilatancy” is proposed for (strongly) stabilized disperse systems. This model is based on the effective volume fraction (EVF) concept, developed in Part I of this series and previously used for the rheological modeling of complex fluids. In such a description, the latter are considered as concentrated dispersions of basic structural units (SUs) — either small, compact clusters or primary particles —, forming large structures at low shear. As shear rate increases, rupturing of these large structures leads to the shear thinning observed prior to dilatancy. The novelty of this model lies in assuming that, beyond the onset of dilatancy, hydrodynamic forces promote, at the expense of basic-SUs, the formation of hydrodynamic clusters as both rheo-optical experiments and numerical simulations recently demonstrated, in contradiction with the (classical) theory based on a shear induced disruption of particle layering. Dilatancy directly results from the increase of the EVF of the dispersion, closely related to the increasing volume of continuous phase imprisoned inside hydroclusters whose size grows as the shear rate increases. Predictions of the model are discussed in comparison with the Mayn features observed in a large number of dilatant dispersions, especially the volume fraction dependences of viscosity and critical shear rates (onset of dilatancy, maximum and discontinuity in viscosity) also the effects of particle size, polydispersity and suspending fluid viscosity.

Keywords

Type
Research Article
Copyright
© EDP Sciences, 1998

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)