During the last decades a considerable effort has been made on the computation of the isothermal flow of viscoelastic fluids. In fact the activities related to this particular field of non-Newtonian fluid mechanics have focused on the following questions: which type of constitutive equation describes non-Newtonian fluid behaviour; how to measure fluid parameters; and what type of computational scheme leads to reliable, stable and cost-effective computer programs. During the same period, typical non-Newtonian fluid phenomena have been experimentally examined, such as the flow through a...