The flow of complex fluids, including polymers and other types of soft matter, has had a growing scientific and technological interest in the last decades. The main rheological characteristics of these materials span from shear-thinning, observed in polymer solutions and melts, passing through strain-softening/hardening, viscoelasticity and reaching instabilities related with flow segregation in the form of shear-banding and yield-stress. In this talk, the latest model-variant of the Bautista-Manero-Puig family is presented, i.e. BMP+(López-Aguilar et al., JNNFM 261 (2018) 188; López-Aguilar et al. JNNFM (2022) 104902), in the context of complex flow deformations in two geometrical configurations: contraction-expansion flow and flow past a sphere. The contraction-expansion geometry considered conforms a modified Couette flow with an obstruction, in which the material experiments a simple shear deformation away from the contraction in a fully-developed flow fashion, and a mixed shear-to-extensional deformation in the constriction zone. This serves the purpose of exposing the BMP+ model predictive capabilities under banding conditions in complex flow. On flow past a sphere, particularly where a smooth sphere settles in a thixo-viscoelastoplastic fluid, solutions obtained with the BMP+ model capture experimental findings on steady and transient oscillating settling velocities (related to negative wake instabilities) and asymmetric yield-fronts for extremely concentrated solutions promoted via the time-dependent, plastic and viscoelastic fluid-features. These flows are solved numerically with advanced tools based on a finite element/volume hybrid algorithm.
Keywords: computational rheology; thixo-viscoelastoplasticity; BMP models; complex flows
J. Esteban López-Aguilar is Associate Professor at the Chemical Engineering Department, Faculty of Chemistry, Universidad Nacional Autónoma de México (UNAM), where he has been a faculty member since 2017. He graduated from UNAM with Bachelors and Masters degrees in Chemical Engineering, followed by a PhD in Chemical Engineering at Swansea University, Wales, UK, institution where he undertook postdoctoral activities at the Zienkiewicz Centre for Computational Engineering and an academic position at the College of Engineering. His research interests are in Non-Newtonian Fluid Mechanics with particular focus on computational rheology and constitutive modelling of complex fluids and soft matter, such as polymer melts and solutions, viscoelastic surfactant solutions, suspensions and biofluids.