A heuristic method for modeling three-dimensional non-Newtonian flows of polymer melts in single-screw extruders

Marschik, Christian; Roland, Wolfgang; Löw-Baselli, Bernhard; Miethlinger, Jürgen

doi:10.1016/j.jnnfm.2017.08.007

Cited by 36 publications

(49 citation statements)

References 17 publications

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“…Since the pioneering and fundamental work of Tadmor and Klein [2], many researchers have attempted to improve the basic models by considering two-dimensional or three-dimensional flow, taking into account the non-Newtonian characteristics of the polymer melt and the actual screw geometry or using a better approach for the thermal analysis, while considering mechanical/thermal coupling (Fenner [156], Lindt et al [157,158], Lawal and Kalyon [159], Spalding et al [160], Syrjala [161,162], and Ilinca and Hetu [163]). Recently, Miethlinger et al [164][165][166] proposed a heuristic method for two-dimensional or three-dimensional modeling of the flow of power-law fluids in metering sections of single screw extruders.…”

Section: Melt Conveying Sectionmentioning

confidence: 99%

Fundamentals of Global Modeling for Polymer Extrusion

et al. 2019

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A review paper is presented on modeling for polymer extrusion for both single screw and twin-screw extrusion. An issue of global modeling is discussed, which includes modeling for solid conveying, melting, melt flow, and co-operation of the screw/die system. The classical approach to global modeling of the extrusion process, which is based on separate models for each section of the screw, i.e., solid transport section, melting and pre-melting sections, and the melt flow section is presented. In this case, the global model consists of the elementary models. A novel continuous concept of global modeling based on CFD (Computational Fluids Dynamics) computations is also presented, and a concept of using the DEM (Discrete Element Method) computation coupled with CFD computations is discussed.

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Section: Melt Conveying Sectionmentioning

confidence: 99%

Fundamentals of Global Modeling for Polymer Extrusion

et al. 2019

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“…In this part, we incorporated the influence of screw rotation into the modeling procedure. To this end, two- and three-dimensional melt-conveying models, presented in [ 30 , 31 , 32 ], were used in the network calculation, replacing the governing pressure-flow equation in the original theory. Moreover, the structure of the flow network was modified to additionally include leakage flow over the main flights.…”

Section: Introductionmentioning

confidence: 99%

Application of Network Analysis to Flow Systems with Alternating Wave Channels: Part B. (Superimposed Drag-Pressure Flows in Extrusion)

et al. 2020

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Due to progress in the development of screw designs over recent decades, numerous high-performance screws have become commercially available in single-screw extrusion. While some of these advanced designs have been studied intensively, others have received comparatively less attention. We developed and validated a semi-numerical network-theory-based modeling approach to predicting flows of shear-thinning polymer melts in wave-dispersion screws. In the first part (Part A), we systematically reduced the complexity of the flow analysis by omitting the influence of the screw rotation on the conveying behavior of the wave zone. In this part (Part B), we extended the original theory by considering the drag flow imposed by the screw. Two- and three-dimensional melt-conveying models were combined to predict locally the conveying characteristics of the wave channels in a discretized flow network. Extensive experiments were performed on a laboratory single-screw extruder, using various barrel designs and wave-dispersion screws. The predictions of our semi-numerical modeling approach for the axial pressure profile along the wave-dispersion zone accurately reproduce the experimental data. Removing the need for time-consuming numerical simulations, this modeling approach enables fast analyses of the conveying behavior of wave-dispersion zones, thereby offering a useful tool for design and optimization studies and process troubleshooting.

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“…In [3,4], it is noted that currently, it is difficult to obtain an exact analytical solution to even a simplified mathematical model of the extrusion process (one-dimensional non-Newtonian flow). Analytical solutions of the problem of the Newtonian fluid isothermal flow in the channel of a single-screw extruder are known, which differ in the way they solve the system of differential equations [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Besides, it is the metering zone that determines the extruder performance [23].Work [4] describes a simple numerical method for solving the problem of the polymer melt flow in the metering zone of the single-screw extruder. The 2D mathematical model takes into account the presence of circulating motion, non-Newtonian behavior of the processed material, and heating of the polymer due to viscous dissipation.In [3,18,19,21,22,25], numerical solutions obtained in a 2D and 3D formulation are approximated by symbolic regression models. The heuristic approach for predicting the main characteristics of the polymer melts flow in the extruder channel is based on genetic programming.…”

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confidence: 99%

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Numerical Simulation of Polymer Solutions in a Single-Screw Extruder

2019

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Single-screw extruders are the most common equipment used for polymer extrusion. The study of the hydrodynamics of a polymer melts flow in the extruder channel is the basis for modeling and understanding the extrusion process. In general form, the extruder includes a straight section with a screw installed in it. In this study, the three-dimensional mathematical modeling of the polymer solutions flow in the metering zone of a single-screw extruder is performed. The influences of the screw geometry (L/D 2 = 1 . . . 3) on the flow structure and the pressure drop are analyzed under a speed rotation up to 60 rpm. Aqueous solutions of 0.5% polyacrylamide (0.5% PAA) and 1.5% sodium salt of carboxymethyl cellulose (1.5% CMC) are considered as the working fluid. Appl. Sci. 2019, 9, 5423 2 of 12 the helical screw channel is unwound and considered as a flat rectangular channel [4,[17][18][19][20][21][22]. Thus, plane-parallel fluid flow in a channel of infinite width is considered instead of direct 3D modeling. Also, the principle of reversed motion is often used (tube rotation is considered at the fixed screw) [4,[17][18][19][20][21][22]. In all works, polymers are considered as shear-thinning fluid [4,[17][18][19][20][21][22].The main functional zones of the extruder are feeding (solids conveying), melting, and metering. The metering zone is the simplest for modeling in a single-screw extruder, since the flow laws of viscous fluids can be applied to the polymer melt flow [23]. In this zone, the polymer is completely molten [24]. Besides, it is the metering zone that determines the extruder performance [23].Work [4] describes a simple numerical method for solving the problem of the polymer melt flow in the metering zone of the single-screw extruder. The 2D mathematical model takes into account the presence of circulating motion, non-Newtonian behavior of the processed material, and heating of the polymer due to viscous dissipation.In [3,18,19,21,22,25], numerical solutions obtained in a 2D and 3D formulation are approximated by symbolic regression models. The heuristic approach for predicting the main characteristics of the polymer melts flow in the extruder channel is based on genetic programming. Speaking about the evolutionary computation in general, it should be noted that they, like any method using an element of randomness, do not guarantee the detection of a global extremum of the objective function (or optimal solution) for a certain time. Their main advantage is that they allow finding a "better" solution to a difficult task in less time than other methods.In contrast with the standard flat-plate model of the unwound screw channel (2D), this hydrodynamic problem is solved in a three-dimensional formulation in [17,26]. Authors of the papers consider mathematical modeling of the flow in the metering zone of a plasticizing extruder. The objective of the study was the melting of the polymer composition based on polyethylene.Work [27] presents the results of three-dimensional numerical simulation of the polymer mel...

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A heuristic method for modeling three-dimensional non-Newtonian flows of polymer melts in single-screw extruders

Cited by 36 publications

References 17 publications

Fundamentals of Global Modeling for Polymer Extrusion

Fundamentals of Global Modeling for Polymer Extrusion

Application of Network Analysis to Flow Systems with Alternating Wave Channels: Part B. (Superimposed Drag-Pressure Flows in Extrusion)

Numerical Simulation of Polymer Solutions in a Single-Screw Extruder

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