In recent years, Computational Fluid Dynamics (CFD) have played an ever increasing roll in the design of extruder dies for a variety of products.  Considerations of flow profiles, pressure drop, exposure to excessive shear and temperature are very important to produce optimum product.  Here is a case in point.  The extruder die shown above (only one half of the die is modeled), is for a pasta produced in a star shape.   There are internal distribution holes that are INTENDED to ensure that the product is uniform coming out of the die.  However, what one intends is not always what one achieves. 

This is the flow profile at the outlet of the die.  The redder colors above represent higher flow and the bluer colors represent lower flow.  We can see here that the intent (uniform product) was NOT achieved.  Where the flow is lower, the product will be thinner.  The resulting thickness variations will affect how the product cooks.   If this were a product that would be baked, the thinner regions will tend to be overbaked and perhaps even burnt, while thicker sections will be undercooked.  All of this leads to poor product and higher consumer complaints.