Rheology of concentrated dispersed systems in a low molecular weight matrix

The start of ebullition in quiescent, yield-stress fluids

“…The shear strength effect arises from interactions between small suspended 9 particles, which produce microstructures (e.g. Marangoni and Rogers 2003;Laxton and Berg 2006;Coussot et a!. 1993).…”

“…Flow is laminar-like and confined between static regions when complex fluids are in transition from a quiescent state (Coussot et al 1993). The two-dimensional viscoplastic foam (Princen 1983) is often used as an analog for flowing condensed matter (Morral and Ashby 1974), particularly following an hexagonal array geometry (Khan and Armstrong 1986;Kem et al 2004;Cantat and Delanney 2005).…”

Rhéologie des laves torrentielles

“…Il est cependant possible, avec ces rhéomètres, de tester le mélange eau-argile interstitiel des laves. Mais même dans ce cas relativement simple les expériences doivent être réalisées avec beaucoup de précautions pour obtenir des résultats qui représentent effectivement la loi de comportement du fluide [7,10,14,25]. Les mélanges qui nous concernent font en effet partie de la grande classe des fluides à seuil qui posent de nombreux problèmes expé-rimentaux [26][27] et font encore l'objet de quelques débats conceptuels dans le domaine de la rhéologie.…”

A dissipative particle dynamics model for thixotropic materials exhibiting pseudo-yield stress behaviour

“…The current view of this research area, which we share, of the yield stress as a very viscous transition remains an attractive and useful engineering idea, and that it is a result of a network microstructure generated by inter-particle interactions, which may rupture into smaller clusters by large enough applied stresses and 15 then restores at a low stress level. The network needs time to build up and to disintegrate, and the rheology of the mixture therefore has a time scale; this results in a macroscopic thixotropic and yield stress behaviour, which has been considered one of the most complex phenomena in rheology [1]. For example, in cohesive sediment mixtures, which provide the motivation of this work, clay 20 particles flocculate and then break up under flow conditions.…”

“…exhibit a stable solid form at rest, and liquify once subjected to an applied stress exceeding a critical value -a yield-stress behaviour. This can be qualitatively explained by the forming and destruction of the fluid microstructure [1], and it may be modelled as a thixotropic and yield stress material. In this paper, we propose a mesoscopic model which is able to mimic a thixotropic and yield stress behaviour using a particle-based technique known as dissipative particle dynamics (DPD).…”