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The PAL (Penalized Augmented Lagrangian) method for computing viscoplastic flows: A new fast converging scheme
(2018)
Computation of viscoplastic fluid flows has always been a challenging task. Viscoplastic models are intrinsically discontinuous at the yielded-unyielded interface, which leads to numerical difficulties, because of the ...
Annular pressure-driven flow of a Bingham plastic with pressure-dependent rheological parameters
(2019)
The pressure and temperature dependence of the yield stress is well established in oil drilling. In the present work, the steady, annular pressure-driven flow of a Bingham plastic is considered under the assumption that ...
Start-up plane Poiseuille flow of a Bingham fluid
(2019)
The start-up flow of a Bingham plastic in a channel is considered and Safronchik’s solution [1] for the initial evolution of the yield surface and the core velocity is revisited. Stricter time bounds for the validity of ...
The time-dependent extrudate-swell problem of an Oldroyd-B fluid with slip along the wall
(1998)
We demonstrate that viscoelasticity combined with nonlinear slip acts as a storage of elastic energy generating oscillations of the pressure drop similar to those observed experimentally in extrusion instabilities. We ...
Predictions of structure breakdown, buildup and shear banding in semisolid suspensions
(2008)
When SSM material is subjected to a sudden transient the rate of buildup (aging) is negligible compared to the rate of breakdown (shear rejuvenation). While this is generally true, due to prolonged processing or the geometry ...
Shear rejuvenation, aging and shear banding in yield stress fluids
(2009)
The purpose of this work is to simulate shear rejuvenation and aging effects in shear thinning yield stress fluids in a typical rotational rheometer and to provide a common framework to describe the behavior of yield stress ...
Flow instabilities of Herschel-Bulkley fluids
(2003)
We investigate numerically the interactions of two-dimensional jets of Bingham plastic and Herschel-Bulkley fluids with a vertical surface at a distance from the die exit. This problem simulates the early stages of filling ...
On numerical simulations of polymer extrusion instabilities
(2002)
The objective of this study is mainly to review recent work concerning the numerical modeling of the stick-slip and gross melt fracture polymer extrusion instabilities. Three different mechanisms of instability are discussed: ...