Numerical analysis on the fluidization dynamics of rodlike particles

Nan, Wenguang; Wang, Yueshe; Wang, Jianzhong

doi:10.1016/j.apt.2016.08.015

Cited by 44 publications

(16 citation statements)

References 50 publications

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“…5 compares the time-averaged porosity profiles with both experiments and CFD-DEM results reported in Muller et al [52] at two heights above the distributor plate: 16.4 and 31.2 mm. In general, the present results are comparable with the experimental data but slightly over-predict the porosity especially in the vicinity of the side walls, similar findings are also reported in other validation tests of CFD-DEM methods [54,55]. At the height of 16.4 mm, the maximum difference between the predicted values and the experimental values is within 20% relative to the experimental value.…”

Section: Cfd Solversupporting

confidence: 80%

Coupling CFD-DEM with dynamic meshing: A new approach for fluid-structure interaction in particle-fluid flows

Bayly

Hassanpour

2018

Powder Technology

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Many important engineering applications involve the interaction of free-moving objects with dispersed multiphase flows, however due to the challenge and complexity of modelling these systems, modelling approaches remain very limited and very few studies have been reported. This work presents a new method capable of addressing these problems. It integrates a dynamic meshing approach, used to explicitly capture the flow induced by free-moving large object(s), with a conventional CFD-DEM method to capture the behaviour of small particles in particle-fluid flow. The force and torque acting on the large object due to the fluid flow are explicitly calculated by integrating pressure and viscous stress acting on the object's surface and the forces due to collisions with both the smaller particles and other structures are calculated using a soft-sphere DEM approach. The developed model has been fully implemented on the ANSYS/Fluent platform due to its efficient handling of dynamic meshing and complex and/or free-moving boundaries, thus it can be applied to a wide range of industrial applications. Validation tests have been carried out for two typical gas-solid fluidization cases, they show good qualitative and quantitative agreement with reported experimental literature data. The developed model was then successfully applied to gas fluidization with a large immersed tube which was either fixed or freemoving. The predicted interacting dynamics of the gas, particle and tube were highly complex and highlighted the value of fully resolving the flow around the large object. The results demonstrated that the capability of a conventional CFD-DEM approach could be enhanced to address free-body fluid-structure interaction problems encountered in particle-fluid systems.

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Section: Cfd Solversupporting

confidence: 80%

Coupling CFD-DEM with dynamic meshing: A new approach for fluid-structure interaction in particle-fluid flows

Bayly

Hassanpour

2018

Powder Technology

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“…The drag force is calculated using the scheme proposed by De Felice, which is widely used for spherical particles and nonspherical particles and expressed as:

f_{d, i} = 0.125 C_{D} ρ_{f} π d_{pi}^{2} ε_{i}^{2} ∣ u_{i} - v_{i} ∣ ((), u_{i} - v_{i}) ε_{i}^{- χ}

where χ is empirical coefficient calculated as, χ = 3.7 − 0.65exp[−(1.5 − log 10 Re i ) 2 /2], Re i = ρ f d pi ε i | u i − v i |/ μ f , ρ f is fluid density, d pi is particle diameter, ε i is porosity, u i is fluid velocity, v i is particle translational velocity and C D is the drag coefficient which is obtained by the Hölzer and Sommerfeld drag force model given as:

C_{D} = \frac{8}{Re} \frac{1}{\sqrt{ϕ_{‖}}} + \frac{16}{Re} \frac{1}{\sqrt{ϕ}} + \frac{3}{\sqrt{italicRe}} \frac{1}{ϕ^{3 / 4}} + 0.42 10^{0.4 {(- logϕ)}^{0.2}} \frac{1}{ϕ_{⊥}}

where ϕ is the sphericity of an ellipsoid defined as the ratio of surface area of a sphere being equivalent volume of the ellipsoid to the surface area of the ellipsoid, ϕ ⊥ is the crosswise sphericity, and ϕ ‖ is the lengthwise sphericity. More details of the two sphericity parameters can be referred to Zhou et al and Gan et al…”

Section: Model Descriptionmentioning

confidence: 99%

“…The findings from the previous studies suggest that the fluidization of nonspherical particles is complex as nonspherical particles are anisotropic which results in different particle behaviors and bubble dynamics . However, to date, little efforts have been made on how the bubble properties and dynamics vary with particle shape.…”

Section: Introductionmentioning

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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“…For the case where the gas flow is not introduced into the system, only DEM simulation is utilised. For completeness, we only describe the key features of the simulation method as follows and further information could be found in Nan et al (2016).…”

Section: Simulationsmentioning

confidence: 99%

Analysis of powder rheometry of FT4: Effect of air flow

Nan

Ghadiri

Wang

2017

Chemical Engineering Science

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Understanding of particle flow behaviour as a function of strain rate is of great interest in many items of equipment of industrial processes, such as screw conveyors, impeller mixers, and feeders, etc. The traditional commercial instruments for bulk powder flow characterisation, such as shear cells, operate at low shear strain rates, and are not representative of unit operations under dynamic conditions. In recent years, the FT4 powder rheometer of Freeman Technology has emerged as a widely used technique for characterising particle flow under dynamic conditions of shear strain rate; yet little is known about its underlying powder mechanics. We analyse the effect of gas flow on the flow behaviour of cohesionless particles in FT4 both experimentally and by numerical simulations using the combined discrete element method (DEM) and computational fluid dynamics (CFD). The results show that the effect of gas flow on the flow energy could be described by the resultant fluid-induced drag on the particles above the blade position as the impeller penetrates the bed. The strain rate in front of the blade is mainly determined by the impeller tip speed, and is not sensitive to the gas flow and particle size. The flow energy correlates well with the shear stress in front of the blade. They both increase with the strain rate and are significantly reduced by the upward gas flow.

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Numerical analysis on the fluidization dynamics of rodlike particles

Cited by 44 publications

References 50 publications

Coupling CFD-DEM with dynamic meshing: A new approach for fluid-structure interaction in particle-fluid flows

Coupling CFD-DEM with dynamic meshing: A new approach for fluid-structure interaction in particle-fluid flows

Bubble dynamics in bubbling fluidized beds of ellipsoidal particles

Analysis of powder rheometry of FT4: Effect of air flow

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