Force model considerations for glued-sphere discrete element method simulations

Kodam, Madhusudhan; Bharadwaj, Rahul; Curtis, Jennifer; Hancock, Bruno C.; Wassgren, Carl

doi:10.1016/j.ces.2009.04.025

Cited by 122 publications

(54 citation statements)

References 36 publications

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“…In simulations of the stress response, this brings up questions regarding the proper contact force law for each of these cases. One way around this issue has been to model complex shapes as particles composed of rigidly connected, overlapping spheres or ellipsoids, 5,26,27,29,30,49,50 but we can expect that in many cir-cumstances faceted particles will behave differently. On the experimental side, one general limitation has been that the set of three-dimensional particle shapes available for testing was confined to either naturally occurring sands or soils, commercially available particle types, 15,17 or particles made with special molds.…”

Section: Introductionmentioning

confidence: 99%

Particle shape effects on the stress response of granular packings

et al. 2014

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We present measurements of the stress response of packings formed from a wide range of particle shapes. Besides spheres these include convex shapes such as the Platonic solids, truncated tetrahedra, and triangular bipyramids, as well as more complex, non-convex geometries such as hexapods with various arm lengths, dolos, and tetrahedral frames. All particles were 3D-printed in hard resin. Well-defined initial packing states were established through preconditioning by cyclic loading under given confinement pressure. Starting from such initial states, stress-strain relationships for axial compression were obtained at four different confining pressures for each particle type. While confining pressure has the largest overall effect on the mechanical response, we find that particle shape controls the details of the stress-strain curves and can be used to tune packing stiffness and yielding. By correlating the experimentally measured values for the effective Young's modulus under compression, yield stress and energy loss during cyclic loading, we identify trends among the various shapes that allow for designing a packing's aggregate behavior.

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Section: Introductionmentioning

confidence: 99%

Particle shape effects on the stress response of granular packings

et al. 2014

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“…Sometimes, it becomes very difficult to control the simulation for particles of high aspect ratio, where a small angular motion causes a larger linear deformation. Random packings of cubic and cuboid particles in the cylindrical columns are generated using a glued-sphere Discrete Element Method [31][32][33]. The glued-sphere approach overcomes all these difficulties and provides reasonable accuracy.…”

Section: Packing Generationmentioning

confidence: 99%

Multiscale modeling of fixed-bed reactors with porous (open-cell foam) non-spherical particles: Hydrodynamics

Das

Deen

Kuipers

2018

Chemical Engineering Journal

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A B S T R A C TAn accurate numerical model is proposed to simulate flow through cylindrical fixed-bed reactors with randomly packed porous non-spherical particles. The length scale for flow outside the porous particles (made of open-cell foam) is O (10 ) 2 higher than the size of the internal micro-pores of the particles. To capture the flow at these two different length scales, a multiscale modeling approach, derived using volume averaging theory (VAT), is developed. The flow through and around the porous particles is computed as a single hydrodynamic field in a Cartesian computational domain. The flow within the inter-particle space is fully resolved, whereas, flow at the scale of the intra-particle micro-pores is not resolved and instead represented by closure terms. Random packings of cubic and cuboid particles in cylindrical columns of different diameter are generated using a glued-sphere Discrete Element Method (DEM) approach. The packing structures for different particle-column combinations are analysed. The effects of particle size/shape, column diameter and internal porosity of the particles on the overall pressure drop and flow distribution are investigated. The macroscopic Reynolds number (based on the particle equivalent diameter and the superficial velocity of the bed) is varied from 0.1 to 400. The effect of Reynolds number on pressure drop is analyzed, as well as the reduction in pressure drop due to the presence of the intra-particle pores. In addition, our numerical simulations have helped to elucidate the detailed fluid-solid interaction in complex bi-disperse, dual porosity porous media.

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“…The glued-sphere approximation was used because it is the current state-of-the-art for DEM simulations of tablet-coating processes. It is widely used in the community (5,(26)(27)(28).…”

Section: Dem Simulationmentioning

confidence: 99%

Experimental Analysis of Tablet Properties for Discrete Element Modeling of an Active Coating Process

et al. 2013

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Abstract. Coating of solid dosage forms is an important unit operation in the pharmaceutical industry. In recent years, numerical simulations of drug manufacturing processes have been gaining interest as process analytical technology tools. The discrete element method (DEM) in particular is suitable to model tabletcoating processes. For the development of accurate simulations, information on the material properties of the tablets is required. In this study, the mechanical parameters Young's modulus, coefficient of restitution (CoR), and coefficients of friction (CoF) of gastrointestinal therapeutic systems (GITS) and of activecoated GITS were measured experimentally. The dynamic angle of repose of these tablets in a drum coater was investigated to revise the CoF. The resulting values were used as input data in DEM simulations to compare simulation and experiment. A mean value of Young's modulus of 31.9 MPa was determined by the uniaxial compression test. The CoR was found to be 0.78. For both tablet-steel and tablet-tablet friction, active-coated GITS showed a higher CoF compared with GITS. According to the values of the dynamic angle of repose, the CoF was adjusted to obtain consistent tablet motion in the simulation and in the experiment. On the basis of this experimental characterization, mechanical parameters are integrated into DEM simulation programs to perform numerical analysis of coating processes.

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Force model considerations for glued-sphere discrete element method simulations

Cited by 122 publications

References 36 publications

Particle shape effects on the stress response of granular packings

Particle shape effects on the stress response of granular packings

Multiscale modeling of fixed-bed reactors with porous (open-cell foam) non-spherical particles: Hydrodynamics

Experimental Analysis of Tablet Properties for Discrete Element Modeling of an Active Coating Process

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