Computational Fluid Dynamics

Bierdel, Michael

doi:10.3139/9783446433410.008

Cited by 6 publications

(4 citation statements)

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“…Generally, RT start depends on the maximum speed at which the material is transported through the extruder. CFD simulations and our prior work using 1D simulation confirm that the maximum axial transportation velocity in the screws does not depend strongly on the throughput.…”

Section: Resultssupporting

confidence: 57%

In‐line measurement of residence time distribution in melt extrusion via video analysis

Wahl

Hörl

Kaiser

et al. 2017

Polymer Engineering & Sci

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Residence time distribution (RTD) is an important factor in melt extrusion as it strongly influences the product quality. It can cause degradation of the active pharmaceutical ingredient (API), which can be reduced by shorter mean residence times, and the content uniformity, which can be improved by broadening the RTD caused by axial mixing. In our study, we developed an inline video analysis that to date has mainly been applied offline. For extrusion, hydrophilic polymer and a surfactant were used as a molten matrix, in which an API was embedded. The video analysis consisted of four steps: (1) segmentation of the image to mask the strands, (2) calculation of average color values for the segmented pixels of each frame, (3) fitting of the obtained color curve with an analytical solution, and (4) calculating several RTD measures (e.g., the minimal and mean RT) for better comparison of the results. The RTD measures were responses in the design of experiments (DoE), which included the process parameters screw design, screw speed, and throughput. This analysis clearly showed that screw design had the strongest effect on the RTD measures. The results suggest that video analysis is a suitable tool for inline RTD measurements. POLYM. ENG. SCI., 58:170–179, 2018. © 2017 Society of Plastics Engineers

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Section: Resultssupporting

confidence: 57%

In‐line measurement of residence time distribution in melt extrusion via video analysis

Wahl

Hörl

Kaiser

et al. 2017

Polymer Engineering & Sci

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“…Flow interacting with complex geometries is frequently encountered in many industrial circumstances such as flow in stirred tanks, wave interacting with an oil rig, and mixing in twin screw extruders (TSEs) …”

Section: Introductionmentioning

confidence: 99%

“…Flow interacting with complex geometries is frequently encountered in many industrial circumstances such as flow in stirred tanks, 1 wave interacting with an oil rig, 2 and mixing in twin screw extruders (TSEs). 3 TSEs are widely used in polymer manufacture, chemical industry, and food industry for its excellent mixing and selfcleaning property. With the great development of computer techniques, the problem-solving ability of numerical analysis techniques have been greatly improved in the past three decades.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Flow in Complex Geometries by Using Smoothed Particle Hydrodynamics

Dong

et al. 2020

Ind. Eng. Chem. Res.

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Because of its meshless nature, the smoothed particle hydrodynamics (SPH) is ideally suitable for simulating a complex flow with a free surface and moving boundary. In this paper, we used a parallelized SPH to analyze the complex flow in a two-dimensional (2D) model of a twin screw extruder with a narrow clearance. First, in order to validate our SPH algorithm, a “forced revolving moving boundary model” previously presented by us was also used in this work. The simulation results showed good agreement with the experimental results. In addition, the flow in the full-filled 2D twin screw extruder model was simulated by using SPH and FEM, respectively. The results of both SPH and FEM showed excellent agreement. Meanwhile, we studied the squeeze flow in the intermeshing region of the 2D model in both the full-filled state and half-filled state. We found that a larger velocity scale that is far higher than the circumferential screw velocity must be applied to estimate the speed of sound. Furthermore, the effects of viscosity and gravity on the flow in the partially filled 2D twin screw extruder model were analyzed. This work laid the foundation for the accurate analysis of flow in complex geometries by using SPH.

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“…First principle simulations of the flow in corotating twin‐screw extruders were mainly conducted via mesh‐based CFD (computational fluid dynamics) methods, such as the finite element method (FEM) and the finite volume method (FVM) . These methods require sophisticated remeshing techniques to manage the rotation of the complex, intermeshing screw geometry.…”

Section: Introductionmentioning

confidence: 99%

Analysis of flow and mixing in screw elements of corotating twin‐screw extruders via SPH

2017

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Due to its meshless nature, the smoothed particle hydrodynamics method (SPH) provides high potential for the simulation of free‐surface flows and mixing in complex geometries. We used SPH to analyze the flow inside five typical screw elements of corotating twin‐screw extruders, two conveying elements, two kneading elements and a mixing element. Our results show conveying capabilities, pressure generation and power input for various operation states, completely and partially filled. We conducted a detailed mixing analysis based on tracer particles, which yielded the time evolution of the intensity of segregation for different tracers. From that, we determined exponential mixing rates, which describe the relative decrease of the intensity of segregation per screw revolution and characterize the mixing performance in different operation states. This provides valuable input information for simplified models of extruders, which are relevant to industrial applications and can significantly contribute to the efficient design, optimization and scale‐up of extruders. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2451–2463, 2017

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Computational Fluid Dynamics

Cited by 6 publications

References 0 publications

In‐line measurement of residence time distribution in melt extrusion via video analysis

In‐line measurement of residence time distribution in melt extrusion via video analysis

Numerical Simulation of Flow in Complex Geometries by Using Smoothed Particle Hydrodynamics

Analysis of flow and mixing in screw elements of corotating twin‐screw extruders via SPH

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