Comparison of flow birefringence results with numerical simulation of the hole pressure.
Values of the stress field obtained along the centreline of a rectangular slot placed perpendicular to the flow direction by means of flow birefringence for a polystyrene melt are compared with those obtained numerically. In the first case the Curtiss-Bird model is used in conjunction with a finite element method developed for memory fluids. The numerical results confirm the experimental findings which help explain why the Higashitani and Pritchard theory seems to be valid in spite of the violation of key assumptions in the theory. Because the Curtiss-Bird model does not fit the viscometric data well for the polystyrene melt, results were also obtained using the White-Metzner model. (A)