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Inverse heat transfer analysis in a polymer melt flow within an extrusion die

In forming processes like the extrusion of polymers, the temperature profile in the polymer melt flow through the die can be quite sharp, due to high viscous dissipation and very low heat conductivity. To predict accurately the temperature rise, the inlet temperature profile has to be taken into account. This profile is generally unknown because for creeping flow the temperature field is affected far downstream from the entrance of the die. This numerical study aims to restore the temperature field within the polymer from temperature measurements taken inside the die. The polymer flow is assumed to be an incompressible steady laminar flow of a Newtonian fluid. The numerical solution of the inverse problem is computed by using a classical conjugate gradient method. The analysis is important to decide the location of the thermocouples in an experimental die. The feasibility of restoring the temperature profile is illustrated for different thermal and flow conditions.