Stability and nonlinear dynamics of film blowing

Transient behavior and stability of the film blowing process have been studied using the governing equations consisting of two well-known force balances and a Phan-Thien and Tanner constitutive equation. A newly-devised numerical scheme, which incorporates an orthogonal collocation on finite elements, was employed to yield transient solutions of the film blowing operation which are hitherto difficult to obtain due to severe numerical stability problems when the system is in an instability called draw resonance. Thus obtained simulation results make possible more systematic analysis of draw resonance, e.g., draw resonance criterion based on the traveling times of kinematic waves on the free surfaces, and the effects of fluid viscoelasticity on the stability.