A NOVEL HYBRID NUMERICAL TECHNIQUE TO MODEL 3-D FOUNTAIN FLOW IN INJECTION-MOLDING PROCESSES

A novel hybrid two-dimensional (2-D)/three-dimensional (3-D) numerical technique is presented to model 3-D fountain flows in thin cavities as encountered in injection molding processes. At the fountain flow region. where all three velocity components are significant, the governing 3-D fluid flow equations are solved by using a pressure Poisson formulation. Behind the flow front, where out of plane flows are negligible, the 2-D Hele-Shaw formulation is employed, largely reducing the number of unknowns in comparison to a fully-three-dimensional formulation. Boundary fitted coordinate systems (BFCS) together with the finite difference method (FDM) are used to solve the governing equations on a non-staggered grid. The formulation is capable of handling non-linearities in the material behavior due to the shear-thinning characteristics of typical resin systems. Results are presented for isothermal flow of Newtonian and shear-thinning fluids through diverging and converging flow sections.