An extension of the hard-sphere particle–particle collision model to study agglomeration

Kosinski, Pawel; Hoffmann, Alex C.

doi:10.1016/j.ces.2010.02.012

Cited by 53 publications

(35 citation statements)

References 27 publications

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“…Numerical investigations have attempted to tackle this issue by employing point-particle approaches in conjunction with a hard-sphere model to account for particle-particle interactions (e.g. Ho & Sommerfeld 2002;Kosinski & Hoffmann 2010;Breuer & Almohammed 2015;Sun et al 2018). The hard-sphere model resolves collisions instantaneously by changing the particle velocity according to a restitution coefficient for inelastic collisions.…”

Section: Introductionmentioning

confidence: 99%

Settling of cohesive sediment: particle-resolved simulations

et al. 2018

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We develop a physical and computational model for performing fully coupled, grainresolved Direct Numerical Simulations of cohesive sediment, based on the Immersed Boundary Method. The model distributes the cohesive forces over a thin shell surrounding each particle, thereby allowing for the spatial and temporal resolution of the cohesive forces during particle-particle interactions. The influence of the cohesive forces is captured by a single dimensionless parameter in the form of a cohesion number, which represents the ratio of cohesive and gravitational forces acting on a particle. We test and validate the cohesive force model for binary particle interactions in the Drafting-Kissing-Tumbling (DKT) configuration. Cohesive sediment grains can remain attached to each other during the tumbling phase following the initial collision, thereby giving rise to the formation of flocs. The DKT simulations demonstrate that cohesive particle pairs settle in a preferred orientation, with particles of very different sizes preferentially aligning themselves in the vertical direction, so that the smaller particle is drafted in the wake of the larger one. This preferred orientation of cohesive particle pairs is found to remain influential for systems of higher complexity. To this end, we perform large simulations of 1,261 polydisperse settling particles starting from rest. These simulations reproduce several earlier experimental observations by other authors, such as the accelerated settling of sand and silt particles due to particle bonding, the stratification of cohesive sediment deposits, and the consolidation process of the deposit. They identify three characteristic phases of the polydisperse settling process, viz. (i) initial stir-up phase with limited flocculation; (ii) enhanced settling phase characterized by increased flocculation; and (iii) consolidation phase. The simulations demonstrate that cohesive forces accelerate the overall settling process primarily because smaller grains attach to larger ones and settle in their wakes. For the present cohesion number values, we observe that settling can be accelerated by up to 29%. We propose physically based parametrization of classical hindered settling functions introduced by earlier authors, in order to account for cohesive forces. An investigation of the energy budget shows that, even though the work of the collision forces is much smaller than that of the hydrodynamic drag forces, it can substantially modify the relevant energy conversion processes.

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Section: Introductionmentioning

confidence: 99%

Settling of cohesive sediment: particle-resolved simulations

et al. 2018

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“…Since the two-dimensional geometry is selected for the present study for the conservation of computational costs, the diameter of the resulting agglomerate is based on the equivalent circle approach as in Balakin et al (2012). The velocity of the agglomerate after its formation is computed as reported in Kosinski and Hoffmann (2010). The volume of the liquid bridge that covers the agglomerate is a sum of liquid volumes that covered the particles before the contact.…”

Section: Numerical Simulationsmentioning

confidence: 99%

The collision efficiency of liquid bridge agglomeration

Balakin

Kutsenko

Lavrukhin

et al. 2015

Chemical Engineering Science

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“…Bei noch dichteren Partikelströmungen, d. h. vierfacher Kopplung, gewinnen zusätzlich Kräfte durch Partikel/Partikel‐Interaktionen sowie Partikel/Wand‐Interaktionen an Bedeutung. In der Diskrete‐Elemente‐Methode (DEM) werden hierfür Kontaktmodelle anhand physikalischer Modelle wie Feder‐, Dämpfer‐ und Gleitelemente angenähert , , , wobei zwischen sogenannten Soft‐Sphere‐ und Hard‐Sphere‐Modellen differenziert werden muss.…”

Section: Numerisches Modellunclassified

“…Zur Betrachtung des Partikelverhaltens in der Simulation bieten sich in der Regel zwei unterschiedliche Modelle an [13]. Einerseits werden bei der Euler-Euler-Betrachtung sowohl die Fluidphase als auch die Partikelphase als Kontinuum betrachtet, wobei für beide Phasen Gleichungen für Massen-, Impuls-und Energieerhaltung aufgestellt und gelöst werden (Navier-Stokes-Gleichungen [12,17,18], wobei zwischen sogenannten Soft-Sphere- [19] und Hard-Sphere-Modellen [20] differenziert werden muss.…”

Section: Numerisches Modellunclassified

Simulation of Entrainment by Free‐Falling Bulk Material Depending on Particle‐Size Distribution

Freiberger

Janoske

2017

Chemie Ingenieur Technik

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Verpackungsprozesse von Pulvern aus dem Bereich der Nahrungsmittel und Medikamente finden häufig unter Schutzatmosphäre statt, um bereits während des Dosierprozesses die Sauerstoffkonzentration der umgebenden Gasphase zu reduzieren und damit eine längere Haltbarkeit der Produkte zu garantieren. Eine neue numerische Simulationsmethodik basierend auf einem Lagrange'schen Modell unter Verwendung von OpenFOAM wurde entwickelt, um neue Dosiersysteme im Vorfeld auf ihre Sicherheit bzgl. der Restsauerstoffwerte im Produkt beurteilen zu können. Zur Validierung dienen experimentell ermittelte Grenzwerte. Simulation of Entrainment by Free-Falling Bulk Material Depending on Particle-Size DistributionPackaging processes of food powders and drugs often take place under a protective atmosphere in order to reduce the oxygen concentration of the surrounding gas phase during the dosing procedure, thus guaranteeing a longer shelf life of the products. A novel numerical simulation method based on a Lagrange model using OpenFOAM was developed to evaluate new dosing systems in advance for their safety regarding the residual oxygen level in the product. The results of experimental setups are used for validation.

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An extension of the hard-sphere particle–particle collision model to study agglomeration

Cited by 53 publications

References 27 publications

Settling of cohesive sediment: particle-resolved simulations

Settling of cohesive sediment: particle-resolved simulations

The collision efficiency of liquid bridge agglomeration

Simulation of Entrainment by Free‐Falling Bulk Material Depending on Particle‐Size Distribution

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