3-dimensional modeling of flow of polymeric fluids with various viscosities in an extrusion die using mixed method and tetrahedral elements

this research work is devoted to the development of a mathematical model for the simulation of the flow of polymeric melts through the die region of extruders. a set of governing equations are solved using finite element method. standard galerkin technique is used in conjunction with the mixed scheme to solve the flow equation. due to the non-linear nature of global equations, the picard iteration method is used. the well-known power-law equation was used to describe non-newtonian rheological behavior of the material and the effect of viscosity on the accuracy of model was investigated. in order to create a finite element mesh for the complex geometries of the die, tetrahedral elements were used. therefore, the second order tetrahedral elements (10 nodes) and the first order tetrahedral elements (4 nodes) were used for calculation of velocity and pressure, respectively. to show the applicability of the model, the flow of the polyethylene melts with various viscosities through the die of a single screw extruder were simulated. the validity of the present technique under realistic conditions was confirmed by comparing the model simulation results with the experimental data.