A method is developed to simulate polymer flow field in polymer extrusion dies based on the finite difference scheme. Boundary-fitted coordinate system has been introduced to generate finite difference grid on the die geometry. Three dimensional flow fields are analyzed in polymer extrusion die by this method.
Boundary-fitted coordinate system is defined by a set of elliptic equations in two dimensional space. In this study, transform relations between physical domain and computational domain are adjusted to satisfy Laplace equation and designed to construct three dimensional coordinate system. It ensure smoothness of boundary-fitted coordinate grids. Several boundary conditions are considered to obtain reasonable grids. This boundary-fitted coordinate system exhibits several advantages: boundary condition can be handle easily, and simulation problems become more simple because finite difference scheme can be applied.
The effect of die shape is considered by varying manifold angle and slot thickness. The effect of power-law index is also considered. Decreasing in power-law index of fluid leads to relative increase in flow rate in die center.
