This study investigates the numerical solution of viscous sharp contraction flow using a time-step Taylor-Galerkin-pressure correction finite element method (T-G/P-C). Such complex problfem displays start-up, 4:1contraction creeping flow, shear viscosity and extensional responses. Here, inelastic shear-extensional model is proposed with single power-index response identical in extension, namely...

We formulate a coarse-grained molecular-dynamics model of polymer chains in solution that includes hydrodynamic interactions, thermal fluctuations, nonlinear elasticity, and topology-preserving solvent mediated excluded volume interactions. The latter involve a combination of potential forces with explicit geometric detection and tracking of chain entanglements. By solving this model with numer...

We solve the free boundary problem for the dynamics of a cylindrical, axisymmetric viscoelastic filament stretching in a gravity-driven extensional flow for the Upper Convected Maxwell and Oldroyd-B constitutive models. Assuming the axial stress in the filament has a spatial dependence provides the simplest coupling of viscoelastic effects to the motion of the filament, and yields a closed syst...

Glassy polymers show "strain hardening": at constant extensional load, their flow first accelerates, then arrests. Recent experiments under such loading have found this to be accompanied by a striking dip in the segmental relaxation time. This can be explained by a minimal nonfactorable model combining flow-induced melting of a glass with the buildup of stress carried by strained polymers. With...

Systematic asymptotic methods are used to formulate a model for the extensional flow of a thin sheet of nematic liquid crystal. With no external body forces applied, the model is found to be equivalent to the socalled Trouton model for Newtonian sheets (and fibers), albeit with a modified “Trouton ratio”. However, with a symmetry-breaking electric field gradient applied, behavior deviates from ...

In this contribution we studied the emulsification process carried out in an extensionalflow unit. By means of rigorous population and momentum balances we captured the phenomenological description of the first principles occurring in such unit. The strong feature of our model approach resides in the fully mechanistic description of the governing phenomena. Namely, a population balance equation...