Numerical simulation of entry and exit flows in slit dies

A general‐purpose finite element program has been used to simulate the flow of Newtonian, power‐law, and viscoelastic fluids in the entry and exit regions of a slit die. It was found that shear‐thinning increases the entrance correction while it decreases the exit correction. Shear‐thinning reduces the size of the small corner vortex that forms in the entry flow of a Newtonian fluid. The swelling ratio had a value of 1.196 for Newtonian fluids and decreased as the value of the power‐law index decreased. Viscoelastic calculations were performed using the Criminale‐Ericksen‐Filbey (CEF) constitutive equation. Convergence of the iterative scheme was unattainable for Deborah numbers above 1.0. The results showed a decrease of the entrance correction and an increase of the exit correction with elasticity. Extrudate swell first decreased slightly and further increased with the Deborah number.