One of the interesting features of viscoelastic flow simulations is the prediction of extrudate swelling, which can be larger than their Newtonian counterparts. Running complex 3D flows with a rheologically sophisticated model, however, can be computationally expensive. Therefore, a more simplified approach is needed: one in which you can qualitatively predict the extrudate free surface. This approach is referred to as the “simplified viscoelastic model" or the “light viscoelastic model".