ABSTRACT
A numerical approach is presented that allows one to investigate the linear viscoelastic stability behavior of simplified injection molding flows. Important questions that can be addressed with this approach are: ‘‘What are critical flow conditions for the onset of an instability?’’ and ‘‘How does this relate to the rheology of the polymer?’’An even more intriguing question that can be studied is ‘‘What is the physical mechanism that drives the secondary flow?’’ Important aspects of such a study are the numerical algorithm and the choice of the rheological model. The numerical algorithm is crucial for a correct prediction of the stability behavior of complex flow and, therefore, much attention is paid to the numerical aspects. Most numerical schemes produce approximate solutions that are not real solutions of the original problem. Moreover, the outcome of the stability analysis will depend on the capability of the nonlinear viscoelastic constitutive model to describe real polymer melts.
