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

Recently two groups of researchers have reported numerical results sim ulating the steady how of a KBKZ fluid in torsion free axisymmetric ab rupt contraction geometry. The fluid model used in both cases was a co nstitutive equation chosen to match laboratory behavior of LDPE. In bo th cases, quadratic finite elements were used. Large corner vortices w ere observed in the simulations, similar to those observed in laborato ry experiments. The agreement between the results in the two papers is good. We repeat the experiment, using linear finite elements. Trackin g is performed via an artificial time method, and a novel ''reduced ve locity'' variable is used in our finite element simulation. There is g ood qualitative and quantitative agreement between the results reporte d here and the results previously reported by others. Quantitative mea sures used in the comparison-vortex opening angle, Couette correction, and vortex intensity-are analyzed.