Discrete particle-continuum fluid modelling of gas–solid fluidised beds

Kafui, K.D.; Thornton, Colin; Adams, M.J.

doi:10.1016/s0009-2509(02)00140-9

Cited by 411 publications

(212 citation statements)

References 36 publications

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“…The work done during the compression of the examined granules was calculated according to the above derived relations (38)(39)(40). The energy absorption due to viscoelastic and viscoplastic deformations is neglected in this calculation.…”

Section: Loading-unloading Behaviour Of Granulesmentioning

confidence: 99%

“…In the last ten-fifteen years, these methods found many applications in the mechanics of bulk materials, i.e. flow behaviour and discharge of silos [8,49,50], filling and packing [111], shearing [25,35,47,61,103], heap formation [13,36,65], bed configuration and loading conditions in fall mills [63,69,105], compression behaviour [68,78], mixing and transportation [12,27,44,52,54,107], fluidised bed processes [31,40,41,58,66,90,102,104,110,112], heat exchange processes [41,50].…”

Section: Introductionmentioning

confidence: 99%

“…The time step of DEM calculations that ensures numerical stability is proportional to the mass of the smallest particle in the system [6]. Therefore in the DEM/DPM-models the granules are usually represented as homogeneous particles [31,40,58,66,67,78,110] and the influence of their microstructure is neglected. Based on the assumption of a continuous matter, contact theory and continuum mechanics can be used to describe the mechanical behaviour of a granule without breakage through experimentally observed mechanical parameters like modulus of elasticity, yield point, contact stiffness.…”

Section: Introductionmentioning

confidence: 99%

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Energy absorption during compression and impact of dry elastic-plastic spherical granules

et al. 2010

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The discrete modelling and understanding of the particle dynamics in fluidized bed apparatuses, mixers, mills and others are based on the knowledge about the physical properties of particles and their mechanical behaviour during slow, fast and repeated stressing. In this paper model parameters (modulus of elasticity, stiffness, yield pressure, restitution coefficient and strength) of spherical granules ( γ -Al 2 O 3 , zeolites 4A and 13X, sodium benzoate) with different mechanical behaviour have been measured by single particle compression and impact tests. Starting with the elastic compression behaviour of granules as described by Hertz theory, a new contact model was developed to describe the force-displacement behaviour of elastic-plastic granules. The aim of this work is to understand the energy absorption during compression (slow stressing velocity of 0.02 mm/s) and impact (the impact velocity of 0.5-4.5 m/s) of granules. For all examined granules the estimated energy absorption during the impact is found to be far lower than that during compression. Moreover, the measured restitution coefficient is independent of the impact velocity in the examined range and independent of the load intensity by compression (i.e. maximum compressive load). In the case of repeated loading with a constant load amplitude, the granules show cyclic hardening with increasing restitution coefficient up to a certain saturation in the plastic deformation. A model was proposed to describe the increase of the contact stiffness with the number of cycles. When the load amplitude is subsequently increased, further plastic deformation takes place and the restitution coefficient strongly decreases.

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Section: Loading-unloading Behaviour Of Granulesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Energy absorption during compression and impact of dry elastic-plastic spherical granules

et al. 2010

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“…The proposed method provides an accurate description of the particles' dynamic motions (position and velocity) in accordance with Newton's second law of motion, factoring in the shape, size and material properties of the particles. The DEM coupled with the CFD method has also been proposed for effectively studying the liquid-solid particle interactions and particle motion in two-phase flow (Kafui, Thornton, & Adams, 2002;Tsuji, Kawaguchi, & Tanaka, 1993). This approach uses the DEM and CFD method to iteratively solve for the particle motion and the fluid flow field so as to achieve momentum balance between the liquid and solid phases, while considering the solid particle concentration.…”

Section: Introductionmentioning

confidence: 99%

Transient numerical simulation for solid-liquid flow in a centrifugal pump by DEM-CFD coupling

Huang

Qiu

2015

Engineering Applications of Computational Fluid Mechanics

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The two-phase solid-liquid flow in the computational fluid dynamic (CFD) method is generally analyzed by treating the solid particles as a quasi-fluid element, but this does not take into account the effects of the physical features of the solid particles and collisions among the particles. In this study, the discrete element method (DEM) was coupled with the CFD method in order to analyze the transient two-phase solid-liquid flow in a single-stage centrifugal pump with consideration for the particle-particle and particle-structure interactions. The numerical simulation process involving EDEM and FLUENT is described. Simulations were performed for the water at 25âĎČ at the continuous phase together with 15% of the volume as spherical solid particles (density ρ = 1500 kg/m 3 ) with the diameter ranging from 1 to 3 mm in a random order. The results illustrate the motion of the solid particles in the pump and their effect on the flow performance of the pump in terms of time variation in the head. The velocity fields for the two-phase flow together with the volume fraction distributions and trajectories of the solid particles in the centrifugal pump are also presented.

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“…They attributed that the charge acquisition of the powder initially occurs primarily during the contact between the particles and the cylinder. However, it is extremely difficult to obtain detailed information from each particle in the dynamic system experimentally [15][16][17]. Therefore, the discrete element method coupled with computational fluid dynamics (DEM-CFD) has been widely used to explore the physical and mechanical behaviours of each individual particle and subsequent bulk properties of the particle system.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of contact electrification of non-spherical particles in a rotating drum

Chen

Adams

2015

Powder Technology

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Contact electrification is generally referred to as the charge transfer process between particles during collisions. The transferred charge can be accumulated on the surface of the particles especially for insulating materials with irregular shapes, which can lead to a non-uniform charge distribution and eventually affects the charge accumulation process. In this study, in order to investigate the influence of the particle shape on contact electrification, a sphere-tree multi-sphere method and a contact electrification model are implemented into the discrete element method (DEM) to model the charging process of irregular particles in a rotating drum. Irregular particles with various Sauter mean diameters but the same maximum diameter and equivalent volume diameters are considered. The charge distribution and accumulation on the particles are investigated. It is found that the charge transfer originates from the contact between the particle and the drum due to the contact potential difference and ζ Presently with Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK * Corresponding author: Tel: 01483683506. Email: c.y.wu@surrey.ac.uk 2 initially takes place primarily at the region near the wall of the drum. The charge eventually propagates to the entire granular bed. The charge of the particles increases exponentially to an equilibrium value. For particles with the same maximum diameter, a larger charging coefficient is obtained for the particles with smaller Sauter mean diameters and sphericities, which lead to a faster charge accumulation, while for particles with the same equivalent volume diameter and fill ratio, similar charging coefficients are observed. A non-uniform intra-particle charge distribution is induced on each individual multi-sphere particle.

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Discrete particle-continuum fluid modelling of gas–solid fluidised beds

Cited by 411 publications

References 36 publications

Energy absorption during compression and impact of dry elastic-plastic spherical granules

Energy absorption during compression and impact of dry elastic-plastic spherical granules

Transient numerical simulation for solid-liquid flow in a centrifugal pump by DEM-CFD coupling

Numerical analysis of contact electrification of non-spherical particles in a rotating drum

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