Experimental validation of Lagrangian–Eulerian simulations of fluidized beds

Wachem, van Bgm Berend; Schaaf, van der J John; Schouten, JC Jaap; Krishna, Rajamani; Bleek, van den Cm

doi:10.1016/s0032-5910(00)00389-2

Cited by 94 publications

(58 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It has proven to be a successful tool for studying conventional fluidized beds in literature (He et al, 2012;Luo et al, 2014;van Wachem et al, 2001;Yang et al, 2014;Zhong et al, 2006). For simulating nanoparticle fluidization, as the particle element we use fragments of the large, complex agglomerates present in the bed: the so-called simple agglomerates.…”

Section: Introductionmentioning

confidence: 99%

An adhesive CFD‐DEM model for simulating nanoparticle agglomerate fluidization

et al. 2016

View full text Add to dashboard Cite

Nanoparticle fluidization is an efficient technique to disperse and process nanoparticles. Previous studies show that nanoparticles are not fluidized individually, but as agglomerates with hierarchical fractal structures. In this study, an adhesive CFD-DEM (Computational Fluid Dynamics -Discrete Element Modelling) model is developed, in which we use the simple agglomerate as the discrete element, which are the building blocks of the larger complex agglomerates found in a fluidized bed. We show that both the particle contact model and drag force interaction in the conventional CFD-DEM model need modification for properly simulating fluidization of nanoparticle agglomerates. The contact model includes collision mechanisms of elastic-plastic, cohesive and viscoelastic forces, and the drag force is approximately corrected by a scale factor resulting from particle agglomeration. The model is tested for different cases, including the normal impact, response of angle, and fluidization. The simulation results are promising. With increasing particle cohesive force, the fluidized bed goes from a uniform fluid-like regime, to an agglomerate bubbling regime, and finally to defluidization. The current study provides a tool for gaining insights into the characteristics of nanoparticle fluidization.

show abstract

Section: Introductionmentioning

confidence: 99%

An adhesive CFD‐DEM model for simulating nanoparticle agglomerate fluidization

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Among these approaches, the Lagrangian point-particle approach developed by Crowe, Sharma, and Stock 16 has been extensively applied 6,[17][18][19][20] , and also used in this study. In this approach, solid particles are tracked individually, and their properties, such as position, mass momentum and energy of individual particle, are determined by Newton's second law.…”

Section: Introductionmentioning

confidence: 99%

Four-way coupled simulations of small particles in turbulent channel flow: The effects of particle shape and Stokes number

2015

View full text Add to dashboard Cite

1 Four-way coupled simulations of small particles in turbulent channel flow This paper investigates the effects of particle shape and Stokes number on the behaviour of non-spherical particles in turbulent channel flow. Although there are a number of studies concerning spherical particles in turbulent flows, most important applications occuring in process, energy and pharmaceutical industries deal with non-spherical particles. The computation employs a unique and novel four-way coupling with the Lagrangian point-particle approach. The fluid phase at low Reynolds number (Re τ = 150) is modelled by DNS, while particles are tracked individually.Inter-particle and particle-wall collisions are also taken into account. To explore the effects of particles on the flow turbulence, the statistics of the fluid flow such as the fluid velocity, the terms in turbulence kinetic energy equation, the slip velocity between the two phases and velocity correlations are analysed considering ellipsoidal particles with different inertia and aspect ratio.The results of the simulations show that the turbulence is considerably attenuated, even in the very dilute regime. The reduction of the turbulence intensity is predominant near the turbulence kinetic energy peak in the near wall region, where particles preferentially accumulate. Moreover, the elongated shape of ellipsoids strengthens the turbulence attenuation. In simulations with ellipsoidal particles, the fluid-particle interactions strongly depend on the orientation of the ellipsoids. In the near wall region, ellipsoids tend to align predominantly within the streamwise (x) and wall-normal (y) plane and perpendicular to the span-wise direction, whereas no preferential orientation in the central region of the channel is observed. Important conclusions from this work include: the effective viscosity of the flow is not affected, the direct dissipation by the particles is negligible, and the primary mechanism by which the particles affect the flow is by altering the turbulence structure around the turbulence kinetic energy peak.

show abstract

“…In addition, and equally supportive for the validity of the approach proposed here, the separation of time scales has been previously observed in DEM simulations of fluidized beds. 20 Hence, transient effects can be safely omitted, as a first approximation of course. However, the necessity of introducing such an approximation once again clearly illustrates the difficulties encountered in the Eulerian-Eulerian modeling of flows involving FCC particles.…”

Section: Balance Of Forcesmentioning

confidence: 99%

Derivation, simulation and validation of a cohesive particle flow CFD model

Wachem

Sasic

2007

AIChE Journal

View full text Add to dashboard Cite

A comprehensive physical model describing the agglomeration behavior present during fluidization of fine powders is still missing in literature. A model of balance of forces acting on a single solid particle is introduced, aiming at predicting and locally estimating the size of the agglomerates created in the bed. Computational fluid dynamics (CFD) have been used to investigate the hydrodynamics of a gas-solid fluidized bed operated with particles belonging to group A of Geldart classification.1 The key issue is that, in the gas and particle flow field, both hydrodynamic and interparticle forces are of importance. The model is incorporated into simulations based on an Eulerian approach and using the kinetic theory of granular flow. In the simulations, the closure models describing the hydrodynamics of the solids phase are directly affected by the behavior of the agglomerates. No empirical data or parameters were used to close the model. The simulations are compared with experiments of an independent research group, through the time-averaged solids volume fraction in a fluidized bed operated at different gas velocities. The agreement obtained between the simulation results and data from the literature is very good. Also, it is shown that, under flow conditions treated in this work, agglomerates of size of several single particle diameters are present in the fluidized bed.

show abstract

Experimental validation of Lagrangian–Eulerian simulations of fluidized beds

Cited by 94 publications

References 12 publications

An adhesive CFD‐DEM model for simulating nanoparticle agglomerate fluidization

An adhesive CFD‐DEM model for simulating nanoparticle agglomerate fluidization

Four-way coupled simulations of small particles in turbulent channel flow: The effects of particle shape and Stokes number

Derivation, simulation and validation of a cohesive particle flow CFD model

Contact Info

Product

Resources

About