Pressure-drop and kinematics of viscoelastic flow through an axisymmetric contraction-expansion geometry with various contraction-ratios

Kinematic fields illustrated by flow visualization reveal several different sizes of the corner-vortex, which are related to the relative contributions from the first normal stress difference (N1) and extensional stress throughout the geometry. Transitions from lip-to-corner vortex are related to the transition from shear-dominated to extension-dominated flows. Experimental data, for the Boger fluid on 4:1:4 contraction-ratio, are contrasted against numerical simulation results for a constant-shear-viscosity/extension-hardening FENE-CR model. Trends demonstrate qualitative agreement on epd and vortex activity, which also reveal an interesting interplay between N1 and extensional viscosity.