A <scp>CFD‐DEM</scp> approach to study the breakup of fractal agglomerates in an internal mixer

Frungieri, Graziano; Boccardo, Gianluca; Buffo, Antonio; Marchisio, Daniele; Karimi–Varzaneh, Hossein Ali; Vanni, Marco

doi:10.1002/cjce.23773

Cited by 23 publications

(17 citation statements)

References 38 publications

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“…Once clusters attain a large-enough size, they become more vulnerable to breaking up as a consequence of the viscous stress exerted by the flow field. Therefore, in all of the suspensions in which a size-stabilization effect did not occur, a plateau value of ⟨ P ⟩ is expected to be reached at a later stage, as a consequence of an equilibrium between aggregation and breakage phenomena. − …”

Section: Resultsmentioning

confidence: 99%

Shear-Induced Heteroaggregation of Oppositely Charged Colloidal Particles

2020

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This paper investigates numerically the shearinduced aggregation of mixed populations of colloidal particles leading to the formation of clusters. Suspensions with different amounts of positively and negatively charged colloidal particles are simulated. To resolve the aggregation kinetics and structural properties of the formed clusters, we resort to a mixed deterministic-stochastic simulation method. The method is built on a combination of a Monte Carlo algorithm to sample a statistically expected sequence of encounter events between the suspended particles and a discrete element method built in the framework of Stokesian dynamics to simulate the encounters in a fully predictive manner. Results reveal a strong influence of the composition of the population on both the aggregation kinetics and the aggregate structure. In particular, we observe a size-stabilization phenomenon taking place in the suspension when the relative concentration of the majority particles lies in the range 80−85%; i.e., starting from primary particles, after a short growth period, we observed a cessation of aggregation. Inspection of the aggregate morphology shows that the formed clusters are composed of few minority particles placed in the inner region, while the aggregate surface is covered by majority particles, acting to provide a shielding effect against further growth.

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Section: Resultsmentioning

confidence: 99%

Shear-Induced Heteroaggregation of Oppositely Charged Colloidal Particles

2020

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Section: Introductionmentioning

confidence: 99%

“…This allows one to predict, for instance, particle aggregation, [25] agglomerate restructuring, and the breakup of soft and rigid agglomerates in both simple flow configurations, [26][27][28][29] and in the complex flow field. [30] The present work investigates the mechanical response of three potential drug carrier morphologies to the pathological flow field stress typically encountered in obstructed blood vessels. CFD simulations are used to investigate the effect of an obstruction in three geometries mimicking a clot-obstructed vessel (an axisymmetric obstructed vessel, an asymmetric obstructed vessel, and a microchannel model of stenosis) and to compute a dataset of cluster trajectories.…”

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Response of shear‐activated nanotherapeutic particles in a clot‐obstructed blood vessel by CFD‐DEM simulations

et al. 2022

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In recent years, targeted drug delivery systems have been regarded as a promising solution to enhance the efficiency of treatments against clots in blood vessels. In this context, shear‐activated nanotherapeutics (SANTs) have been recently proposed. These are micrometric clusters of polymeric nanoparticles coated with a clot lysing agent. These drug carriers are stable under normal blood flow conditions, but they can be designed to undergo breakup right on the clot in response to the local increase in the hydrodynamic stress caused by the lumen restriction, effectively concentrating the active agent at the point of need. The aim of this work is to investigate the mechanical response of three potential drug carrier morphologies to the pathological flow field stress, typically encountered in obstructed blood vessels. Computational fluid dynamics simulations have been used to compare the viscous stress in arterial obstructions with the one in a microfluidic device, suitable for in vitro experimental tests. Discrete element method simulations built upon Stokesian dynamics were conducted to estimate the tensile stress distribution acting inside isostatic, random close packing, and hollow drug carriers. The results herein presented constitute a platform for a future experimental campaign and aim at establishing SANTs as a robust and broadly applicable targeting strategy.

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“…In the case of the first aspect, during the separation process, particles agglomerate and break up due to the combined action of Brownian, van der Waals, electrostatic, hydrodynamic, and gravity forces, resulting in changes in the number and size of particles. , The milled coal particles undergo primary agglomeration due to intermolecular forces, and then secondary agglomeration and fragmentation form in the fluidization and sorting process . Computational Fluid Dynamics (CFD)–Population Balance Method (PBM) is an economical and effective method to simulate the evolution process of the number and size of particles caused by agglomeration and fragmentation in the fluidization process …”

Section: Introductionmentioning

confidence: 99%

Study of the Fluidized Separation Process of Irregular Coarse-Grained Pulverized Coal Agglomerates Based on Modified Computational Fluid Dynamics─Population Balance Method

Zheng

et al. 2022

ACS Omega

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In this work, the agglomeration, fragmentation, and separation process of coarse-grained pulverized coal agglomerates (CGPCA) obtained from a power plant were achieved using gas–solid fluidized bed sorting and analyzed through a combination of numerical simulations and actual experiments with CGPCA. To study the polydispersity and irregularity of CGPCA, the CGPCA surface fractal dimension was calculated using fractal dimension combined with scanning electron microscopy. The two-section fractal dimension of the particle size distribution was obtained by fitting the logarithmic particle size distribution of CGPCA. On the basis of the obtained data, the polydisperse particle drag force model, the agglomeration kernel function, and the breakage kernel function were modified. Thus, an irregular polydisperse gas–solid two-phase Eulerian–Eulerian model was constructed to simulate the sorting process of CGPCA in the fluidized bed. The results of the numerical simulation investigation were compared with the experimental results and showed that the simulation data, which considered the two section fractal dimension, was in better agreement with the experimental results. The cumulative logarithmic distribution of CGPCA’s size was segmented and fitted. The values of the two section fractals of the agglomerates were determined as D = 1.014 and D = 2.401, respectively. Analysis revealed that the optimal separation efficiency working condition in the simulation process, providing the highest separation efficiency of 54.7%, was generated at air velocity of 1.21 m/s.

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A CFD‐DEM approach to study the breakup of fractal agglomerates in an internal mixer

Cited by 23 publications

References 38 publications

Shear-Induced Heteroaggregation of Oppositely Charged Colloidal Particles

Shear-Induced Heteroaggregation of Oppositely Charged Colloidal Particles

Response of shear‐activated nanotherapeutic particles in a clot‐obstructed blood vessel by CFD‐DEM simulations

Study of the Fluidized Separation Process of Irregular Coarse-Grained Pulverized Coal Agglomerates Based on Modified Computational Fluid Dynamics─Population Balance Method

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