Previously developed polymer melt flow analysis and design sensitivity analysis methods are extended here to include various Generalized Newtonian Fluid (GNF) models. These Hele-Shaw-based simulations were applied to a polymer sheeting die design where numerical optimization was used to determine the best die cavity half-height distribution to minimize the pressure drop through the die while enforcing a die exit velocity uniformity constraint. The design optimization included multiple operating conditions where a ‘fixed’ region of the die was defined such that it would not be changed once the die is machined. In this approach, ‘adjustable’ features of the die cavity (i.e., the choker bar) are modified for various melt flows in an optimal manner consistent with the overall design objectives. Changes in the die cavity half-height during the optimization are provided below along with the optimal choker bar gap half-height and optimal melt velocity at the die exit under various operating conditions for LDPE.

Optimization-Based Design of Polymer Sheeting Dies Using Generalized Newtonian Fluid Models. Smith, D.E. and Q. Wang. Polymer Engineering and Science, 45(7):953-965, 2005.

An Optimization-Based Approach to Compute Sheeting Die Designs for Multiple Operating Conditions. Smith, D.E. and Wang, Q. 45^th AIAA/ASME/ASCE/AHS/ASC SDM Conference, Palm Springs, CA, April 19-22, 2004.

• U.S. National Science Foundation