We investigate the transient viscoelastic behavior of weakly strain-hardening fluids in filament stretching devices during uniaxial elongation and following the cessation of stretching. The numerical results are compared with experimental observations on a concentrated shear-thinning polystyrene solution which is well characterized by a multi-mode Giesekus model. The finite element computations...

Many micro-organisms swim through gels and non-Newtonian fluids in their natural environments. In this paper, we focus on micro-organisms which use flagella for propulsion. We address how swimming velocities are affected in nonlinearly viscoelastic fluids by examining the problem of an infinitely long cylinder with arbitrary beating motion in the Oldroyd-B fluid. We solve for the swimming veloc...

This work presents the development of a weakly compressible smoothed particle hydrodynamics (WCSPH) model for simulating two-dimensional transient viscoelastic free surface flow which has extensive applications in polymer processing industries. As an illustration for the capability of the model, the extrudate or die swell behaviors of second-order and Olyroyd-B polymeric fluids are studied. A s...

We experimentally investigate the interaction between a pair of bubbles ascending in stagnant viscoelastic shear-thinning fluid. In particular, we focus on effect bubble size, across velocity discontinuity, bubble-bubble interaction. Compared to drafting–kissing–tumbling (DKT) behavior Newtonian fluids, fluid exhibit drafting–kissing–dancing (DKD) phenomenon. dancing phase, repeatedly interchan...

Movies of the breakup of viscous and viscoelastic drops in the high speed airstream behind a shock wave in a shock tube have been reported by Joseph, Belanger and Beavers [1999]. A Rayleigh-Taylor stability analysis for the initial breakup of a drop of Newtonian liquid was presented in that paper. The movies, which may be viewed at http://www.aem.umn.edu/ research/Aerodynamic_Breakup, show that...

The flow of viscoelastic fluids is an area in which analytical results are difficult to attain, yet can provide invaluable information. We develop a weak-coupling expansion that allows for semi-analytical computations of viscoelastic fluid flows coupled to immersed structures. In our method, a leading-order polymeric stress evolves according to a Newtonian velocity field, and this stress is use...

This paper presents a new and efficient method for computing the flow of a non-Newtonian fluid. The approach is based on two independent concepts: Time-dependent simulation of viscoelastic flow: A new decoupled algorithm, presented in P. Saramito, Simulation numerique d'ecoulements de fluides viscoelastiques par eRments finis incompressibles et une methode de directions alternees; applications,...

The effects of elasticity on filament thinning and breakup are investigated in microchannel cross flow. When a viscous solution is stretched by an external immiscible fluid, a low 100 ppm polymer concentration strongly affects the breakup process, compared to the Newtonian case. Qualitatively, polymeric filaments show much slower evolution, and their morphology features multiple connected drops...

in this paper, the transient inertial viscoelastic flow around a circular cylinder is investigated numerically. a second order finite-volume method is used to increase the numerical accuracy. here, the giesekus model is used as the constitutive equation. this nonlinear model has prominent ability in describing normal stress differences and viscosity in power-law regions. the impacts of the elas...

We theoretically study the linear stability of Saffman–Taylor problem where a viscous Newtonian fluid (with viscosity ηl) displaces an Upper Convected Maxwell (UCM) ηr) in rectilinear Hele-Shaw cell. The dispersion relation is given by roots cubic polynomial with coefficients depending on wavenumber along several dimensionless groups as parameters. Using Routh–Hurwitz criterion, we show that ra...