Analysis of viscoelastic polymer melt flow

In recent years significant progress has been made in the experimental and numerical analysis of viscoelastic polymer melt flow. From the numerical point of view a number of well established mixed finite element formulations have been developed that are sufficiently stable, robust and efficient to analyze a range of two and three dimensional flow problems. Typical examples are the so-called DEVSS/DG and DEVSS/SUPG methods. Experimentally, an increasing variety of flow geometries has become available, satisfying requirements such as near twodimensionality of the flow (i.e. a depth-to-height aspect ratio of at least 8 in the whole flow domain). The measurement resolution of fringe patterns has improved significantly by the application of lasers such that accurate measurements can be made at critical locations in the geometry. Furthermore, the use of Mueller calculus allows the prediction of the observable fringe patterns in three dimensional flow geometries. Crucial to the quantitative prediction of velocity and stress fields in inhomogeneous flows is the availability of reliable constitutive models. Within the class of differential models, the multi-mode versions of the Giesekus and PTT model have been the most widely applied. Recently, a new generation of models [3] has been developed based on the concepts of the Pompom model. These Pompom based models are a major step forwards in describing the rheology of (polyethylene) melts. The objective of this contribution is to investigate the performance of an enhanced, single equation version of the Pompom model in predicting the inhomogeneous flow of an LDPE melt in the cross-slot geometry. This particular version quantitatively predicts available rheometrical shear and elongational data of a set of polymer melts, see Verbeeten et al