An analytical model for steady coextrusion of viscoplastic fluids in thin slit dies with wall slip

Kalyon, Dilhan M.

doi:10.1002/pen.21580

Cited by 16 publications

(9 citation statements)

References 46 publications

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“…Since slip velocity depends on several factors, such as fluid and surface properties as well as the surrounding conditions like pressure and temperature, 47,54,96,101,204 the slip coefficient is system-dependent. 55,67,113 This dependency allows the above-mentioned simplification of the relation between slip velocity and wall shear stress as a direct proportionality, where the other factors are absorbed in the slip coefficient.…”

Section: Slip Quantificationmentioning

confidence: 99%

Slip at Fluid-Solid Interface

Sochi

2011

Polymer Reviews

158

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The `no-slip' is a fundamental assumption and generally-accepted boundary condition in rheology, tribology and fluid mechanics with strong experimental support. The violations of this condition, however, are widely recognized in many situations, especially in the flow of non-Newtonian fluids. Wall slip could lead to large errors and flow instabilities, such as sharkskin formation and spurt flow, and hence complicates the analysis of fluid systems and introduces serious practical difficulties. In this article, we discuss slip at fluid-solid interface in an attempt to highlight the main issues related to this diverse complex phenomenon and its implications.Comment: 69 page

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Section: Slip Quantificationmentioning

confidence: 99%

Slip at Fluid-Solid Interface

Sochi

2011

Polymer Reviews

158

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“…These models can include all of the features already discussed in this article, such as a description of the changes in the rheological properties of the material along the device, the presence of partially-or completely-filled zones, the wall slip effect on the flows [83][84][85][86][87], etc. The resulting 3D models can be used to achieve some dynamic studies, such as the analysis of the instabilities of the die flow [88,89] or the description of the chaotic motion inside screw elements by dynamic tools (Lyapunov exponents, Poincare sections and particle tracking), which enable the study of the mixing conditions in hot-melt extrusion processes [90][91][92].…”

Section: Distributed Parameter Modelsmentioning

confidence: 99%

A Review of Dynamic Models of Hot-Melt Extrusion

2016

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Hot-melt extrusion is commonly applied for forming products, ranging from metals to plastics, rubber and clay composites. It is also increasingly used for the production of pharmaceuticals, such as granules, pellets and tablets. In this context, mathematical modeling plays an important role to determine the best process operating conditions, but also to possibly develop software sensors or controllers. The early models were essentially black-box and relied on the measurement of the residence time distribution. Current models involve mass, energy and momentum balances and consists of (partial) differential equations. This paper presents a literature review of a range of existing models. A common case study is considered to illustrate the predictive capability of the main candidate models, programmed in a simulation environment (e.g., MATLAB). Finally, a comprehensive distributed parameter model capturing the main phenomena is proposed.

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“…The flow through circular pipes and plane slits has many applications in physical and biological sciences and engineering and hence it has been investigated in the past by many researchers (e.g. [1][2][3][4][5][6][7][8][9][10][11][12]) using various methods of fluid dynamics. Recently we proposed the use of Euler-Lagrange variational principle [13] to resolve the flow of generalized Newtonian fluids through circular pipes.…”

Section: Introductionmentioning

confidence: 99%

Variational Approach for Resolving the Flow of Generalized Newtonian Fluids in Circular Pipes and Plane Slits

Sochi

2015

Mathematical Problems in Engineering

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In this paper, we use a generic and general variational method to obtain solutions to the flow of generalized Newtonian fluids through circular pipes and plane slits. The new method is not based on the use of the Euler-Lagrange variational principle and hence it is totally independent of our previous approach which is based on this principle. Instead, the method applies a very generic and general optimization approach which can be justified by the Dirichlet principle although this is not the only possible theoretical justification. The results that were obtained from the new method using nine types of fluid are in total agreement, within certain restrictions, with the results obtained from the traditional methods of fluid mechanics as well as the results obtained from the previous variational approach. In addition to being a useful method in its own for resolving the flow field in circular pipes and plane slits, the new variational method lends more support to the old variational method as well as for the use of variational principles in general to resolve the flow of generalized Newtonian fluids and obtain all the quantities of the flow field which include shear stress, local viscosity, rate of strain, speed profile and volumetric flow rate. The theoretical basis of the new variational method, which rests on the use of the Dirichlet principle, also provides theoretical support to the former variational method.

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An analytical model for steady coextrusion of viscoplastic fluids in thin slit dies with wall slip

Cited by 16 publications

References 46 publications

Slip at Fluid-Solid Interface

Slip at Fluid-Solid Interface

A Review of Dynamic Models of Hot-Melt Extrusion

Variational Approach for Resolving the Flow of Generalized Newtonian Fluids in Circular Pipes and Plane Slits

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