Effect of lift force and hydrodynamic torque on fluidisation of non-spherical particles

Mema, Ivan; Mahajan, Vinay V.; Fitzgerald, Barry; Padding, JT Johan

doi:10.1016/j.ces.2018.10.009

Cited by 50 publications

(38 citation statements)

References 60 publications

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“…Mema et al showed that the lift force can have significant influence on the particle velocities parallel to the direction of the gravity and the particle orientation depends on the hydrodynamic torque. However, the lift force and the hydrodynamic torque may become important under conditions such as higher Reynolds numbers and for particles with a more pronounced nonspherical shape . Since the Reynolds number is very low in this study, the lift force and the rotational motion is not considered.…”

Section: Model Descriptionmentioning

confidence: 99%

Bubble dynamics in bubbling fluidized beds of ellipsoidal particles

Shrestha

Kuang

et al. 2019

AIChE Journal

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This article presents a CFD-DEM study on the effect of particle shape on bubble dynamics in bubbling fluidized beds. The particles used are ellipsoids, covering from disk-type to cylinder-type. The phenomena such as bubble coalescence and splitting are successfully generated, and the results are compared with literature, showing a good agreement. The results demonstrate that the bubble forming/rising regions and patterns are influenced significantly by particle shape. Ellipsoidal particles have asymmetrical bubble patterns with two or more circulation vortices while the bubbles for spherical particles form at the bed centerline and rise through the center of the bed. Hence, the vertical mass flux at the bed centerline for spheres is always positive, and ellipsoids have negative or positive vertical mass fluxes. The solid mixing estimated based on the dispersion coefficient revealed poor mixing for ellipsoids. Spherical particles have a larger bubble size and higher bubble rising velocity than ellipsoids.

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Section: Model Descriptionmentioning

confidence: 99%

Bubble dynamics in bubbling fluidized beds of ellipsoidal particles

Shrestha

Kuang

et al. 2019

AIChE Journal

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“…This is an important characteristic of nonspherical particles, because orientation of the particles relative to the fluid flow affects the magnitude of the drag force they experience and also increases the importance of shape induced lift force and hydrodynamic torque. 2,7,8 Figure 10 shows the effect of changing the gas velocity on particle orientation relative to the z-axis. To avoid the effect of the slightly higher tracer density, discussed in Section 3, the free-board region and lower part of the bed, and close to the distributor plate are excluded from the averaging.…”

Section: Particle Orientationmentioning

confidence: 99%

“…The horizontal orientation of the particles in the lower free-board region is the consequence of hydrodynamic torque. 2 In this region, particles move more-or-less individually and without the perturbing influence of neighboring particles they tend to orient horizontally in a planar upward flow due to the stabilizing effect of hydrodynamic torque. Next to the walls, particles still tend to align with the y-axis but an increase of alignment with the z-axis can also be seen in that region.…”

Section: Particle Orientationmentioning

confidence: 99%

“…Fluidization of elongated particles such as cylinders, ellipsoids, and spherocylinders has been the topic of several numerical investigations. [1][2][3][4][5] More fundamental research has also been conducted to obtain a better understanding of the hydrodynamic forces acting on individual elongated particles. [6][7][8][9] Experimental investigations for validation of computational models for dense gas-particle flows are still quite scarce, especially for three dimenensional (3D) systems.…”

Section: Introductionmentioning

confidence: 99%

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Fluidization of spherical versus elongated particles: Experimental investigation using magnetic particle tracking

et al. 2019

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In biomass processing fluidized beds are used to process granular materials where particles typically possess elongated shapes. However, for simplicity, in computer simulations particles are often considered spherical, even though elongated particles experience more complex particle-particle interactions as well as different hydrodynamic forces. The exact effect of these more complex interactions in dense fluidized suspensions is still not well understood. In this study we use the magnetic particle tracking technique to compare the fluidization behavior of spherical particles to that of elongated particles. We found a considerable difference between fluidization behavior of spherical versus elongated particles in the time-averaged particle velocity field as well as in the time-averaged particle rotational velocity profile. Moreover, we studied the effect of fluid velocity and the particle's aspect ratio on the particle's preferred orientation in different parts of the bed, which provides new insight in the fluidization behavior of elongated particles.

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“…Magnetic Particle Tracking is a very powerful technique to study both particle translation and rotation in a full 3‐D cylindrical fluidized bed. With this technique new reference data has been generated for validation of CFD‐DEM models . It is expected that the effects of drag, hydrodynamic torque and particle–particle and particle‐wall interactions will largely effect the appropriateness of these models, which can now be validated with this technique.…”

Section: Discussionmentioning

confidence: 99%

Magnetic particle tracking for nonspherical particles in a cylindrical fluidized bed

et al. 2017

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In granular flow operations, often particles are nonspherical. This has inspired a vast amount of research in understanding the behavior of these particles. Various models are being developed to study the hydrodynamics involving nonspherical particles. Experiments however are often limited to obtain data on the translational motion only. This paper focusses on the unique capability of Magnetic Particle Tracking to track the orientation of a marker in a full 3-D cylindrical fluidized bed. Stainless steel particles with the same volume and different aspect ratios are fluidized at a range of superficial gas velocities. Spherical and rod-like particles show distinctly different fluidization behavior. Also, the distribution of angles for rod-like particles changes with position in the fluidized bed as well as with the superficial velocity. Magnetic Particle Tracking shows its unique capability to study both spatial distribution and orientation of the particles allowing more in-depth validation of Discrete Particle Models.

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Effect of lift force and hydrodynamic torque on fluidisation of non-spherical particles

Cited by 50 publications

References 60 publications

Bubble dynamics in bubbling fluidized beds of ellipsoidal particles

Bubble dynamics in bubbling fluidized beds of ellipsoidal particles

Fluidization of spherical versus elongated particles: Experimental investigation using magnetic particle tracking

Magnetic particle tracking for nonspherical particles in a cylindrical fluidized bed

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