Numerical Modeling of Shear Banding Formation in Rheometry

The paper is dedicated to the numerical modeling of materials, such as complex fluids, which exhibit intrinsic material instability in viscometric flows. Some notorious examples of complex fluids are polymer solutions, colloids, solid dispersions in liquids and soft solids (pastes, creams, greases). Most of these materials disclose structure instability beyond critical deformations and stresses, being characterized by the existence of a non-monotonic steady flow curve and the shear banding formation. Numerical simulations performed with a generalized Newtonian model confirm the existence of the shear banding in the gap of the rheometers, as a consequence of the coexisting asymptotic steady shear rates of the velocity distribution under constant shear stress. The present findings are consistent with the previous results published in literature and confirmed by experiments performed in our laboratory.