A model is presented for simulating two‐dimensional, nonisothermal film casting of a viscous polymer. The model accommodates the effects of inertia and gravity, and allows the thickness of the film to vary across the width, but it excludes film sag and die swell. Based on the simulation results, three factors are shown to contribute to reducing neck‐in and promoting a uniform thickness: the self‐weight of the material, for low viscosity polymers; nonuniform thickness and/or velocity profiles at the die; and cooling of the film, especially when localized cooling jets are employed.

This paper presents a new numerical algorithm for 2D nonisothermal time‐stepping simulations of a nonlinear viscoelastic cast film process. A significant contribution of the algorithm is that an updated Lagrangian description of motion is employed, as opposed to the more conventional Eulerian description generally used for continuous polymer processing simulations. Furthermore, use is made of a Perzynatype constitutive equation, which is different from what is usually employed for molten polymers. The constitutive equation accommodates viscoelasticity, extensional thinning/thickening, and strain‐hardening. This new numerical algorithm can find the steady‐state film properties, and it can predict the onset of instability by observing draw resonance. The critical draw ratio is determined from the response problem, which means that the mathematical complications of the more common linear stability analysis are avoided. In terms of the stability of the film, it was observed that stability is decreased by extensional thinning, strain‐hardening, and higher relaxation times, and stability is increased by higher heat transfer coefficients and higher ratios of air‐gap length to die width.

His research interests include the use of design recovery and symbolic execution in automating the numerical analysis of scientific software. Meng has a BS in mathematics and engineering from Queen's University.

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This paper argues that the reliability of engineering computation can be significantly improved by adopting software engineering methodologies for requirements analysis and specification. The argument centers around the fact that the only way to judge the reliability of a system is by comparison to a specification of the requirements. This paper also points to methods for documenting the requirements. In particular, a requirements template is proposed for specifying engineering computation software. To make the mathematical specification easily understandable by all stakeholders, the requirements documentation employs the technique of using tabular expressions. To clarify the presentation, this paper includes a case study of the documentation for a system for analyzing statically determinant beams.