On the optimal numerical time integration for Lagrangian DEM within implicit flow solvers

Tuley, Robert James; Danby, Matthew; Shrimpton, John S.; Palmer, Mark

doi:10.1016/j.compchemeng.2009.10.003

Cited by 27 publications

(7 citation statements)

References 58 publications

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“…Another simplifying assumption is made regarding the Young modulus of the moving particles, whereas the Young modulus is reduced one order of magnitude from the original value. Conducting a sensitivity analysis confirmed the findings of several other studies (Kawaguchi et al, 1997;Ketterhagen et al, 2007;Ketterhagen et al, 2005;Tuley et al, 2010;Hogue and Newland, 1994;Pérez, 2008;Silbert et al, 2001;Kruggel-Emden et al, 2007) that lowering the stiffness within a certain range does not affect the results of the DEM simulation. This is due to the fact that although changing the stiffness constant does affect the duration of a single collision, the velocity and trajectory of the particle after the collision is only dependent on the coefficient of restitution and the coefficients of friction.…”

Section: Dem Studysupporting

confidence: 79%

Numerical Prediction of the Bulk Density of Granular Particles of Different Geometries

Samiei

Berhe

Peters

2014

KONA

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The Discrete Element Method (DEM) is increasingly used to simulate the motion of granular material in engineering devices. The most widely used shape to model granular particles is the sphere due to its simplicity which facilitates computations. However, with increasing advancement and popularity of the DEM approach, a more accurate representation of real granular shapes is becoming intensely important. This paper is an attempt to predict the bulk density of granular particles of cylindrical shape by DEM. The method used to model tube-like particles is the composite method where the tube-like particle is composed of a number of spherical sub-shapes. The results show that the DEM prediction of the bulk density of tube-like particles were accurate provided that a sufficient number of spherical sub-shapes was used to construct the particle. In addition, the bulk density of granular particles in the shape of 32-face polyhedrons was also investigated. It was shown that 32-face polyhedrons can be approximated as spheres provided that the rolling resistance of the shape is taken into consideration.

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Section: Dem Studysupporting

confidence: 79%

Numerical Prediction of the Bulk Density of Granular Particles of Different Geometries

Samiei

Berhe

Peters

2014

KONA

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“…The damping coefficients are η n,ij = 2| ln e| k n m eff /(π 2 + ln 2 e) and η t,ij = ( 2 7 )η n,ij , where m eff = m i m j /(m i + m j ) is the effective mass of the two contacting particles or a particle contacting an infinite mass wall, and e = 0.9 is the restitution coefficient [61,62]. The symplectic Euler integration algorithm [63][64][65] is used to update particle positions and velocities. The simulation time step is chosen to be it is smaller than the critical time step, which is one-tenth of the minimal natural oscillation period of the spring-mass system [41,[66][67][68].…”

Section: Appendix a Discrete Element Methods Simulationsmentioning

confidence: 99%

Continuum modelling of segregating tridisperse granular chute flow

et al. 2018

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Segregation and mixing of size multidisperse granular materials remain challenging problems in many industrial applications. In this paper, we apply a continuum-based model that captures the effects of segregation, diffusion and advection for size tridisperse granular flow in quasi-two-dimensional chute flow. The model uses the kinematics of the flow and other physical parameters such as the diffusion coefficient and the percolation length scale, quantities that can be determined directly from experiment, simulation or theory and that are not arbitrarily adjustable. The predictions from the model are consistent with experimentally validated discrete element method (DEM) simulations over a wide range of flow conditions and particle sizes. The degree of segregation depends on the Péclet number, , defined as the ratio of the segregation rate to the diffusion rate, the relative segregation strength between particle species and, and a characteristic length , which is determined by the strength of segregation between smallest and largest particles. A parametric study of particle size, , and demonstrates how particle segregation patterns depend on the interplay of advection, segregation and diffusion. Finally, the segregation pattern is also affected by the velocity profile and the degree of basal slip at the chute surface. The model is applicable to different flow geometries, and should be easily adapted to segregation driven by other particle properties such as density and shape.

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“…one of the most commonly-used collisional force model is the nonlinear viscoelastic model, consisting of two components, i.e. elastic and viscous forces (Brilliantov et al, 1996;Haff and Anderson, 1993;Silbert et al, 2001;Tuley et al, 2010).…”

Section: Particle-particle Midair Collisionsmentioning

confidence: 99%

“…The particle motion and wind flow equations are integrated by predictor-corrector method AB3AM4; that is, 3-order Adamas-Bashforth method to perform prediction and 4-order Adams-Moulton method to perform correction. One of the main advantages of using such multi-step integration method is that the accuracy of results is not sensitive to the detection of exact moments of collision (Tuley et al, 2010). The charge transfer between the colliding pairs are caused by their asymmetric contact and can be determined by Eqs.…”

Section: Model Implementationmentioning

confidence: 99%

Effects of three-dimensional electric field on saltation during dust storms: An observational and numerical study

Zhang

Zhou

2019

Preprint

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<p><strong>Abstract.</strong> Particle tribo-electrification being ubiquitous in nature and industry, potentially plays a key role in dust events, including the lifting and transport of sand and dust particles. However, the properties of electric field (E-field) and its influences on saltation during dust storms remain obscure as the high complexity of dust storms and the existing numerical studies mainly limited to one-dimensional (1-D) E-field. Here, we quantify the effects of real three-dimensional (3-D) E-field on saltation, through a combination of field observations and numerical modelling. The 3-D E-fields in the sub-meter layer from 0.05 to 0.7&#8201;m above the ground during a dust storm are measured at Qingtu Lake Observation Array site. The measured results show that each component of the 3-D E-field data nearly collapses on a single 3-order polynomial curve when normalized. Interestingly, the vertical component of the 3-D E-field increases with increasing height in the saltation layer during dust storms. Such 3-D E-field data close to the ground within a few centimeters has never been reported and formulated before. Using the discrete element method, we then develop a comprehensive saltation model, in which the tribo-electrification between particle-particle midair collisions is explicitly accounted for, allowing us to evaluate the tribo-electrification in saltation properly. By combining the results of measurements and modelling, we find that although the vertical component of the E-field (i.e. 1-D E-field) inhibits sand transport, 3-D E-field enhances sand transport substantially. Furthermore, the model predicts that 3-D E-field enhances the total mass flux by up to 63&#8201;%. This suggests that a truly 3-D E-field consideration is necessary if one is to explain precisely how the E-field affects saltation during dust storms. These results will further improve our understanding of particle tribo-electrification in saltation and help to provide more accurate characterizations of sand and dust transport during dust storms.</p>

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On the optimal numerical time integration for Lagrangian DEM within implicit flow solvers

Cited by 27 publications

References 58 publications

Numerical Prediction of the Bulk Density of Granular Particles of Different Geometries

Numerical Prediction of the Bulk Density of Granular Particles of Different Geometries

Continuum modelling of segregating tridisperse granular chute flow

Effects of three-dimensional electric field on saltation during dust storms: An observational and numerical study

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