STEADY FLOWS OF VISCOELASTIC FLUIDS IN AXISYMMETRICAL ABRUPT CONTRACTION GEOMETRY - A COMPARISON OF NUMERICAL RESULTS

Recently two groups of researchers have reported numerical results simulating the steady how of a KBKZ fluid in torsion free axisymmetric abrupt contraction geometry. The fluid model used in both cases was a constitutive equation chosen to match laboratory behavior of LDPE. In both cases, quadratic finite elements were used. Large corner vortices were observed in the simulations, similar to those observed in laboratory experiments. The agreement between the results in the two papers is good. We repeat the experiment, using linear finite elements. Tracking is performed via an artificial time method, and a novel ''reduced velocity'' variable is used in our finite element simulation. There is good qualitative and quantitative agreement between the results reported here and the results previously reported by others. Quantitative measures used in the comparison-vortex opening angle, Couette correction, and vortex intensity-are analyzed.