title: Transient shear banding in time-dependent fluids.
abstract: We study the dynamics of shear-band formation and evolution using a simple rheological model. The description couples the local structure and viscosity to the applied shear stress. We consider in detail the Couette geometry, where the model is solved iteratively with the Navier-Stokes equation to obtain the time evolution of the local velocity and viscosity fields. It is found that the underlying reason for dynamic effects is the nonhomogeneous shear distribution, which is amplified due to a positive feedback between the flow field and the viscosity response of the shear thinning fluid. This offers a simple explanation for the recent observations of transient shear banding in time-dependent fluids. Extensions to more complicated rheological systems are considered.
authors.affiliation: Departament d'Estructura i Constituents de la Matèria, Facultat de Física, Universitat de Barcelona, Diagonal, 647, E-08028 Barcelona, Catalonia, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Illa
authors.forename: Antti
authors.initials: A
authors.lastname: Puisto
authors.forename: Arttu
authors.initials: A
authors.lastname: Lehtinen
authors.forename: Mikael
authors.initials: M
authors.lastname: Mohtaschemi
authors.forename: Mikko J
authors.initials: MJ
authors.lastname: Alava
mesh_terms: D003198:Computer Simulation; D008956:Models, Chemical; D008958:Models, Molecular; D012212:Rheology / Q000379:methods*; D033081:Shear Strength; D012996:Solutions / Q000737:chemistry*; D014783:Viscosity
chemical_list: D012996:Solutions