In blown film extrusion, the polymer is melted in an extruder and the hot melt is pumped through a die to form a thin-walled tube, which is simultaneously axially drawn and radially expanded. Industrial installations can produce more than a ton an hour of film, ranging in thickness usually from 0.01 to 0.5mm. Computer simulation had an enormous impact in die design for reducing film thickness variation and for eliminating stagnant flow areas which could produce local polymer degradation. Such simulations are usually based on some sort of Hele-Shaw flow approximation of a Generalized Newtonian Fluid through the spiral die channels and occasional 3-D simulations Mathematical modeling of blown film bubble formation is carried out on the basis of the thin membrane approximation for the prediction of bubble shape, velocity, thickness, temperature, strain rates and stresses. The standard bubble shape and the high-neck wine glass shape can be predicted as explained in J. Vlachopoulos and V. Sidiropoulos “Die Flow Analysis and Mathematical Modeling of Film Blowing” Chapter 4, T. Kanai and G.A. Campbell (Editors) “Film Processing Advances” Hanser (2014). The rheological properties influence the bubble shape, however, in industrial installations, the bubble shape is controlled by mechanical means and cooling air jets impinging on the bubble, externally and internally. Instabilities are significantly reduced by devices that change the opening to suit an appropriate blow up ratio, bubble cages and bubble guides. There is a dichotomy between academic research and technological progress. While most modern blown film lines are multilayer (frequently more than 7), academic papers are nearly always restricted to modeling of monolayer bubble formation to predict shape and any associated instabilities. In industry, the bubble shape is really controlled by mechanical means.A proposal will be made on how approach the modeling problem by assuming the bubble shape as a parameter.