Simulation of asymmetrical multilayer flat film coextrusion regarding slip at the wall and interfacial slip at the polymer-polymer interface

This work deals with the simulation of the viscous flow of polymers in flat film coextrusion regarding asymmetrical films as well as slip at the wall and slip at the polymer-polymer interface. A one dimensional finite volume approach is used to calculate complex flows of generalized Newtonian materials using numerous damped numerical solvers. This iterative approach is neither depending on the numbers of layers used, nor on the mathematical models of the viscosity, the wall slip or the interfacial slip. Furthermore, the work shows how this one-dimensional simulation can be done using standard spreadsheet software. By that means, it contributes largely to the simplification of dimensioning feed blocks for coextrusion. Moreover, the results compare the velocity profiles and the pressure gradient resulting from the application of three different rheological models. It is clearly shown, that the application of the power-law approach can result in much higher pressure compared to the results determined by utilizing the more realistic Carreau approach.