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In this article we report on progress in the development of software tools for fluid flow prediction in the polymer processing industry. This involves state‐of‐the‐art numerical techniques and the study of a number of non‐trivial model flow problems, in an effort to investigate realistic transient problems relevant to industrial processes. Here we study particularly the effects of variations in non‐Newtonian and heat transfer properties of the flowing materials in the flows, both throughout the transient development period and at steady‐state.

This article focuses on the comparative study of annular wire‐coating flows with polymer melt materials. Different process designs are considered of pressure‐ and tube‐tooling, complementing earlier studies on individual designs. A novel mass‐balance free‐surface location technique is proposed. The polymeric materials are represented via shear‐thinning, differential viscoelastic constitutive models, taken of exponential Phan‐Thien/Tanner form. Simulations are conducted for these industrial problems through distributed parallel computation, using a semi‐implicit time‐stepping Taylor‐Galerkin/pressure‐correction algorithm. On typical field results and by comparing short‐against full‐die pressure‐tooling solutions, shear‐rates are observed to increase ten fold, while strain rates increase one hundred times. Tube‐tooling shear and extension‐rates are one quarter of those for pressure‐tooling. These findings across design options, have considerable bearing on the appropriateness of choice for the respective process involved. Parallel finite element results are generated on a homogeneous network of Intel‐chip workstations, running PVM (Parallel Vitual Machine) protocol over a Solaris operating system. Parallel timings yield practically ideal linear speed‐up over the set number of processors.

A semi‐implicit Taylor‐Galerkin/pressure‐correction algorithm of a transient finite element form is applied to analyse the flow instabilities that commonly arise during reverse‐roller coating. A mathematical model is derived to describe the solvent coating applied to the underside of the sheet, assuming that the lacquer is a Newtonian fluid and considering the flow between application roller and foil. Here, we have investigated the effects of temporal instabilities, caused by adjustment of nip‐gap width and foil‐position, extending our previous steady‐state analysis. Foil shifting is found to have a significant influence upon pressure and lift on the foil, drag on the roller, and free coating profiles. This would result in process instabilities, such as chatter and flow‐lines. In contrast, nip‐gap adjustment has no influence on the coating finish.

We introduce a second‐order accurate time‐marching pressure‐correction algorithm to accommodate weakly‐compressible highly‐viscous liquid flows at low Mach number. As the incompressible limit is approached (Ma ≈ 0), the consistency of the compressible scheme is highlighted in recovering equivalent incompressible solutions. In the viscous‐dominated regime of low Reynolds number (zone of interest), the algorithm treats the viscous part of the equations in a semi‐implicit form. Two discrete representations are proposed to interpolate density: a piecewise‐constant form with gradient recovery and a linear interpolation form, akin to that on pressure. Numerical performance is considered on a number of classical benchmark problems for highly viscous liquid flows to highlight consistency, accuracy and stability properties. Validation bears out the high quality of performance of both compressible flow implementations, at low to vanishing Mach number. Neither linear nor constant density interpolations schemes degrade the second‐order accuracy of the original incompressible fractional‐staged pressure‐correction scheme. The piecewise‐constant interpolation scheme is advocated as a viable method of choice, with its advantages of order retention, yet efficiency in implementation.

To use a behavioral measure of legitimacy to study how differences in negotiating style and status affect the legitimacy of persons in high-power network positions. Predictions include (1) that powerful network actors who negotiate using a pro-group style will maintain legitimacy better than will those who negotiate selfishly and (2) those higher in status will be granted more legitimacy both before and after exchange than powerful actors lower in status.

An experimental study in which participants were connected in networks to powerful partners who were portrayed as consistently high or low on several status characteristics. Both before and after exchange, participants evaluated partners on a number of dimensions and made decisions on whether to vote to join a coalition to take the partner's power away, a direct behavioral indicator of legitimacy.

High-power partners lost legitimacy over the course of exchange irrespective of whether they negotiated in pro-group or selfish ways, and irrespective of whether they were high or low in status. This effect was pronounced for partners who negotiated selfishly. Although partner status predicted legitimacy prior to exchange, legitimacy evaluations after exchange appeared entirely driven by the partner's negotiating style (how the power was used) and not by status.

The project introduces a new behavioral measure of legitimacy that correlated highly with self-report items and should be of value in future research. The study also indicates promising directions for future research that might disentangle effects of power and status on legitimacy, along with adjudicating among explanations for why this study did not find status effects on legitimacy.

Basic science, sometimes called “curiosity-driven research” at the National Science Foundation and other places, starts with a question that somehow stays in the mind, nagging for an answer. Such questions really are “puzzles”; they arise in an intellectual field or context, asking someone to fit pieces to an improving but incomplete picture of the social world. What makes a worthwhile puzzle is a missing part in understanding the picture, or a new piece of knowledge that does not seem to fit among other parts. Sometimes creative theorists can imagine a solution to one of the holes in the puzzle. If they are also empirical scientists, they devise ways to get evidence bearing on their ideas, and some of those ideas survive to give more complete and detailed pictures of the world. This chapter is the story of puzzles and provisional solutions to them, developed by dozens of men and women investigating status processes and status structures, using a coherent perspective, for over half a century.¹

The numerical simulation of two‐dimensional incompressible complex flows of viscoelastic fluids is presented. The context is one, relevant to the food industry (dough kneading), of stirring within a cylindrical vessel, where stirrers are attached to the lid of the vessel. The motion is driven by the rotation of the outer vessel wall, with various stirrer locations. With a single stirrer, both a concentric and an eccentric configuration are considered. A double‐stirrer eccentric case, with two symmetrically arranged stirrers, is also contrasted against the above. A parallel numerical method is adopted, based on a finite element semi‐implicit time‐stepping Taylor‐Galerkin/pressure‐correction scheme. For viscoelastic fluids, constant viscosity Oldroyd‐B and two shear‐thinning Phan‐Thien/Tanner constitutive models are employed. Both linear and exponential models at two different material parameters are considered. This permits a comparison of various stress, shear and extensional properties and their respective influences upon the flow fields generated. Variation with increasing speed of vessel and change in mixer geometry are analysed with respect to the flow kinematics and stress fields produced. Optimal kneading scenarios are commended with asymmetrical stirrer positioning, one‐stirrer proving better than two. Then, models with enhanced strain‐hardening, amplify levels of localised maxima in rate‐of‐work done per unit power consumed. Simulations are conducted via distributed parallel processing, performed on work‐station clusters, employing a conventional message passing protocol (PVM). Parallel results are compared against those obtained on a single processor (sequential computation). Ideal linear speed‐up with the number of processors has been observed.

This article is concerned with the numerical simulation of a reverse roller‐coating process, which involves the computation of Newtonian viscous incompressible flows with free‐surfaces. A numerical scheme is applied of a transient finite element form, a semi‐implicit Taylor‐Galerkin/pressurecorrection algorithm. For free‐surface prediction, we use kinematic boundary adjustment with a mesh‐stretching algorithm. In the present work, an alloy sheet (foil) passes over a large roller and then a smaller applicator roller, which provides the in‐feed. In combination, the applicator roller, the foil and the fluid form part of the underside coating mechanism. The aim of this study is to investigate fundamental aspects of the process, to ultimately address typical coating instabilities. These may take the form of chatter and starvation. A uniform coating thickness is the desired objective. A mathematical model is derived to describe the solvent coating applied to the underside of the sheet, assuming that the lacquer is a Newtonian fluid. In particular, the work has concentrated on the flow patterns that result and a parameter sensitivity analysis covering the appropriate operating windows of applied conditions. Effects of independent variation in roll‐speed and foil‐speed are investigated, to find that maxima in pressure, lift and drag arise at the nip and are influenced in a linear fashion.

A numerical study on the stretching of a Newtonian fluid filament is analysed. Stretching is performed between two retracting plates, moving under constant extension rate. A semi‐implicit Taylor‐Galerkin/pressure‐correction finite element formulation is employed on variable‐structure triangular meshes. Stability and accuracy of the scheme is maintained up to large Hencky‐strain levels. A non‐uniform radius profile, minimum at the filament mid‐plane, is observed along the filament‐length at all times. We have found maintenance of a suitable mesh aspect‐ratio around the mid‐plane region (maximum stretch zone) to restrict early filament break‐up and consequently solution divergence. As such, true transient flow evolution is traced and the numerical results bear close agreement with the literature.