Numerical simulation of polymer coextrusion flows: A criterion for detection of "wave" interfacial instability onset

Abstract

Non-isothermal calculation of flow history dependent viscoelastic stresses in a coextrusion die is performed using the 8-mode modified Leonov constitutive equation. It is shown that a heuristic criterion based on the difference of normal stress differences across the layer interfaces in the merging area may be used to potentially detect the onset of interfacial instabilities.