COMPARISON OF CALCULATED WITH MEASURED FLOW-FIELDS IN THE GAP BETWEEN2 ROTATING ROLLS

Velocity, pressure, temperature, and stress fields are calculated for the flow of a polymer between two counterdirectionally rotating rolls. The rheological behavior of the polymer is described by the Carreau e quation, while elasticity is neglected. The results of the numerical c alculations are compared with measurements. The stress field is measur ed by the birefringence method. The local principal stresses in the fl uid are determined from the measured anisotropy of the sheared fluid f or the penetrating monochromatic light by means of the stress optical law. The equations of motion and continuity are solved with a Finite E lement Method (FEM) based on the Galerkin weighted residual method. Th e computer code is combined with a Boundary Element Method (BEM) algor ithm using the Dual Reciprocity Method (DRM) to solve the coupled equa tion of energy. Results are shown for a shear-thinning polyisobutene m elt in a calender with totally submerged rolls. The calculated results for the principal stress differences are compared to the measured res ults and confirm fairly well. The influence of friction is discussed. (C) 1994 John Wiley & Sons, Inc.