The plastics industry uses runner systems extensively to distribute hot polymers into multiple injection molds. When a runner system is improperly balanced, variations in the temperature and residence time of the material being fed to the mold invariably result, often leading to product degradation. Even in a geometrically-balanced runner system, passage of the material around bends and corners can lead to maldistribution due to the shear-rate and temperature dependency of viscosity. Shear heating can also cause local hot spots, which can degrade the quality of the polymer and the final product. Fluent flow modeling software is ideal for this application, because we make it easy to model complex geometries quickly, and thermal results are very quickly obtained, as you can see from the example shown here.

Temperature distribution in an unbalanced runner system. Note the local hot spots.