Modeling of Non-Spherical, Elongated Particles for Industrial Suspension Flow Simulation

Redlinger-Pohn, Jakob Dominik; König, Lisa Maria; Kloss, Christoph; Goniva, Christoph; Radl, Stefan

doi:10.7712/100016.1838.7321

Cited by 5 publications

(4 citation statements)

References 35 publications

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“…The dimensionless fluid shear rate is 33.67.The terminal settling velocity vs, as well as the resulting sedimentation time, ts was calculated for fibre orientation normal and parallel to the direction of gravity. Calculation of the drag force and thus the settling velocity of a sedimenting fibre is given in Redlinger-Pohn et.al (Redlinger- Pohn et al, 2016)…”

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confidence: 99%

Mechanistic understanding of size-based fiber separation in coiled tubes

Redlinger-Pohn

Jagiello

Bauer

et al. 2016

International Journal of Multiphase Flow

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Understanding separation of poly-disperse particle suspensions according to the particles size is of great importance to product quality. Previous experimental studies of suspension flow through coiled tubes report different results for spherical and elongated particles, e.g., larger and thus heavier elongated particles are faster than smaller ones. We use Euler-Lagrange simulations, as well as experiments, to measure the residence time distribution of fibres with different size in coiled tubes with different curvatures. Fluid flow through the coiled tubes was simulated as toroidal flow, i.e., the pitch of the tube was neglected. Fibres are one-way coupled to the fluid, and their movement in the cross section, as well as their orientation is predicted based on the assumption of an infinitely dilute suspension. We find that in coiled, dilute suspension flow of fibres the ratio of particle settling velocity to the secondary flow speed determines the fibre motion in the tube cross section. For low Reynolds number and thus larger effect of gravitation, fibres are found to concentrate in distinct orbits. Long fibres form flocs propagating through the torus whilst small fibres are well mixed and thus retained in the tube. We found that fibre-fibre interaction and the formation of flocs and not fibre-fluid interaction is key to the size based separation.

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confidence: 99%

Mechanistic understanding of size-based fiber separation in coiled tubes

Redlinger-Pohn

Jagiello

Bauer

et al. 2016

International Journal of Multiphase Flow

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“…Redlinger-Pohn et al [135] studied the suspension of elongated particles in a closed torus. This was done in order to approximate the flow of fibers in a coiled tube.…”

Section: Hydraulic Conveyancementioning

confidence: 99%

A Novel Approach For Analyzing Mixing Quality In Solid-Liquid Stirred Tanks Via Coupled Computational Fluid Dynamics - Discrete Element Method And Electrical Resistance Tomography

Tran¹

2021

Preprint

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The mixing quality of a solid-liquid stirred tank operating in the turbulent regime was investigated, numerically and to an extent experimentally. Simulations were performed by coupling Computational Fluid Dynamics (CFD) and the Discrete Element Method (DEM). The results were evaluated against experimental data obtained using Electrical Resistance Tomography (ERT). This facilitated a novel and more rigorous assessment of CFD-DEM coupling – i.e. based on the spatial distribution of particle concentrations. Furthermore, a new mixing index definition was developed to quantify suspension quality to work in tandem with existing dispersion mixing indexes. This provides a more complete interpretation of mixing quality. In this work, it was found that the model underestimated suspension and dispersion due to model limitations associated with mesh size and fluid-particle interaction models. Furthermore, the predicted mixing quality was sensitive to changes in the drag model, including other fluid-particle interaction forces in simulations, and variations in certain particle properties

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“…The resulting wall normal position depends on the orientation and length of the fibre. For the case of fibres orientated in flow direction, this would be the fibre half-length [23,26]. For arbitrary orientated fibres a linear increase in concentration is noted until reaching the fibre half-length [5,11].…”

Section: Dilute Suspensionsmentioning

confidence: 99%

Length-selective separation of cellulose fibres by hydrodynamic fractionation

Redlinger-Pohn

König

Radl

2017

Chemical Engineering Research and Design

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A hydrodynamic fraction device (HDF) was developed based on the principle of spontaneous fibre network formation and subsequent segregation of fibres and fines in cellulose pulp. Separation is most successful in the so-called "annulus plug flow" regime, which is demonstrated for various combinations of fibre concentration and Reynolds number. In this regime, fibres form a network in the channel center, surrounded by fluid with relative low concentration of fibres and large concentration of fines. As in flow channel separation, wall bounded fluid-containing the fines fraction-is removed from the main flow via sidechannels. Long fibres that form a network exit via the main channel. Via an array of experiments we demonstrate precise fractionation of cellulose pulp at a typical cut size of 1 mm. Also, we show that higher Reynolds numbers lead to a dispersion of the fibre network, and consequently a lower sharpness of cut-increasing the fibre concentration leads to a lower yield of shorter fibres. While variation of geometrical parameters did not affect the separation performance, the design of the HDF clearly impacts its capacity.

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Modeling of Non-Spherical, Elongated Particles for Industrial Suspension Flow Simulation

Cited by 5 publications

References 35 publications

Mechanistic understanding of size-based fiber separation in coiled tubes

Mechanistic understanding of size-based fiber separation in coiled tubes

A Novel Approach For Analyzing Mixing Quality In Solid-Liquid Stirred Tanks Via Coupled Computational Fluid Dynamics - Discrete Element Method And Electrical Resistance Tomography

Length-selective separation of cellulose fibres by hydrodynamic fractionation

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