Numerical Analysis for Polymer Melt Flow in Injection Molding

A numerical method using a finite element approach is proposed to analyze the unsteady three-dimensional flow of power-law fluids with moving free surfaces. Based on the fractional step method and Rational Runge-Kutta (RRK) method for mass and momentum equations, this method is a semi-explicit scheme with unconditional numerical stability for pseudoplastic fluids. The transfer equation for the volume fraction of molten polymer is solved to calculate the moving free surface. The energy equation is divided into the transfer and diffusion equations. These equations are solved by a modified characteristic curve method and the RRK method, respectively. The calculation results are obtained by the present method for two box-shaped cavity flows. These are compared with the experimental results using a short-shot injection technique. Experimental and computational findings agree within 5% regarding location of the meltfronts.