FINITE ELEMENT SIMULATION OF FOUNTAIN FLOW IN INJECTION MOLDING.

The term 'fountain effect' was apparently coined to describe the flow field near an advancing interface in a capillary when a moving fluid is replacing another immiscible fluid. The objective of this paper is to present the results of a finite element simulation of Newtonian and shear-thinning fluids advancing with a free front inside two-dimensional channels and tubes. Special attention is given to the shape of the free surface and the velocity and pressure fields behind it. These flow details are necessary for the determination of which fluid particles reach the mold surface to form a solidifying layer. Fountain flow in the front region contributes significantly to the orientation of polymer molecules and fillers near the molded particle surface and near weld lines. Fountain flow is also important in reaction injection molding because it influences the local viscosity and the extent of reaction.