We have implemented the log-conformation method for two-dimensional viscoelastic flow in COMSOL, a commercial high-level finite element package. The code is verified for an Oldroyd-B fluid flowing past a confined cylinder. We are also able to describe the well-known bistability of the viscoelastic flow in a crossslot geometry for a FENE-CR fluid, and we describe the changes required for perform...

In this paper we discuss simulation techniques for a rising bubble in viscoelastic fluids via numerical methods based on high order FEM. A level set approach based on the work in [9] is used for interface tracking between the bubble and the surrounding fluid. The two matters obey the Newtonian and the Oldroyd-B constitutive law in the case of a viscoelastic fluid while the flow model is given b...

The thermal instability of a rotating Rivlin-Ericksen viscoelastic fluid in the presence of uniform vertical magnetic field is considered. For the case of stationary convection, Rivlin-Ericksen viscoelastic fluid behaves like a Newtonian fluid. It is found that rotation has a stabilizing effect, whereas the magnetic field has both stabilizing and destabilizing effects. Graphs have been plotted ...

v

Polymer solutions and melts are viscoelastic; they exhibit fluidlike behavior in steady shear, but the initial response to an imposed deformation involves a material-dependent transient that may be many orders of magnitude longer than time scales associated with instrument inertia. Intrinsic material time scales can be identified with the dynamics of the macro­ molecular chains. Shaping process...

Flagella beating in complex fluids are significantly influenced by viscoelastic stresses. Relevant examples include the ciliary transport of respiratory airway mucus and the motion of spermatozoa in the mucus-filled female reproductive tract. We consider the simplest model of such propulsion and transport in a complex fluid, a waving sheet of small amplitude free to move in a polymeric fluid wi...

In this paper, we consider an infinitely long viscoelastic thread in a tube filled with a Newtonian fluid. We apply Jeffreys model as the rheological relation for the thread. The thread moves due to a constant pressure gradient, but so slowly that the quasi-static creeping flow approximation is applicable. We investigate the effect of the ratio of viscosities, fluid elasticity, confinement and ...

Fig. 1. Plot of the magnitude of the velocity (upper left) and axial component (x-direction) of the stress (upper right) of a steady viscoelastic fluid flow in a simple planar channel with an enlargement (motivated by a simple model of a small arterial aneurysm). This component of the stress is the most pronounced at the entrance and exit of the enlargement. The magnitude of the shear stress (c...

The thermal convection of compressible Walters’B′ Rotating viscoelastic fluid is considered in the presence of uniform vertical magnetic field. By applying normal mode analysis method, the dispersion relation has been derived and solved analytically. For stationary convection, Walters’B′ viscoelastic fluid behaves like an ordinary (Newtonian) fluid. It is found that rotation has a stabilizing e...