Stratified two‐phase flog of molten polymers in circular dies

A theoretical study has been carried out on the steady, axisymmetric two‐phase flow of molten polymers in circular dies. For both fluids, the shear rate dependence of the viscosity is described by a power law and the temperature dependence by an exponential function. Taking into account viscous dissipation, a numerical program has been developed to predict the radial position of the interface between the two fluids, the developing temperature and velocity fields, the shear rates, the shear stresses, the pressure drop as well as the field of shear deformation and the residence time distribution for different thermal boundary conditions. The numerical program is applied to the flow of a high‐viscous polymer melt, (high density polyethylene), surrounded by a small annulus of less viscous polymer ni lt, (low density polyethylene). Computed results are shown graphically.