Numerical simulation of granular materials by an improved discrete element method

Fortin, Jérôme; Millet, Olivier; Saxcé, Géry de

doi:10.1002/nme.1209

Cited by 63 publications

(51 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…(10)- (12) are shown in Figure 4, where, for differentiability, only the distributions under the shear velocity 0.68 m/s are given. From Figure 4, it is indicated that all of the PDFs for absolute values of upwind and downwind horizontal velocities, vertical velocities and resultant velocities follow an exponential density function, whereas, the angular velocities which lie within − -1500 1100 rev/s distribute with a normal density function, and its symmetrical axis is 0.4693 ω = − rev/s.…”

Section: Resultsmentioning

confidence: 99%

“…In this paper, the cooling method [12] is required to produce an initial sand bed for particle-bed collision simulation. In order to emulate natural sand particle-bed collision, natural sand particles are sampled from sand dune in southern area of the Tengger desert in China, and their particle diameters obey a lognormal distribution (see Figure 2) [13] .…”

Section: Simulation Of Mixed-size Particle-bed Collisionsmentioning

confidence: 99%

See 1 more Smart Citation

A probability density function of liftoff velocities in mixed-size wind sand flux

Zheng

Zhu

Xie

2008

Sci. China Ser. G-Phys. Mech. Astron.

View full text Add to dashboard Cite

With the discrete element method (DEM), employing the diameter distribution of natural sands sampled from the Tengger Desert, a mixed-size sand bed was produced and the particle-bed collision was simulated in the mixed-size wind sand movement. In the simulation, the shear wind velocity, particle diameter, incident velocity and incident angle of the impact sand particle were given the same values as the experimental results. After the particle-bed collision, we collected all the initial velocities of rising sand particles, including the liftoff angular velocities, liftoff linear velocities and their horizontal and vertical components. By the statistical analysis on the velocity sample for each velocity component, its probability density functions were obtained, and they are the functions of the shear wind velocity. The liftoff velocities and their horizontal and vertical components are distributed as an exponential density function, while the angular velocities are distributed as a normal density function.wind sand flux, mixed-size particle diameter, liftoff velocity, probability density function (PDF), discrete element method (DEM) It is obvious that the liftoff velocities of sand particles with different diameters are of crucial importance for the prediction of wind sand flux. Therefore, a key issue in the research of wind erosion is to clarify the dynamical characteristic of sand particles lifting from the natural sand bed surface due to particle-bed collision [1] , that is, with a given wind shear velocity, to obtain the probability density function (PDF) of liftoff velocities of sand particles rising from the mixed-size sand bed.There have already been many studies on the PDF of liftoff velocities of sand particles since the mid and later 1980s, e.g., deducing from the experimental photographs of 100 glass grains' trajectories with diameters ranging from 0.35 mm to 0.71 mm. Anderson and Hallet [2] thought that the probability densities of liftoff velocities are subject to an exponential function or a Gamma function with regard to shear wind velocity; Willetts and Rice [3] had direct observations on particle-bed collisions with 100 spherical and planar sand particles using a cine-camera. The diameters of sand

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Simulation Of Mixed-size Particle-bed Collisionsmentioning

confidence: 99%

A probability density function of liftoff velocities in mixed-size wind sand flux

Zheng

Zhu

Xie

2008

Sci. China Ser. G-Phys. Mech. Astron.

View full text Add to dashboard Cite

show abstract

“…Here, we have studied the simple case of nondeformable and nonpenetrable particles in two dimensions with the computational programme MULTICOR [Fortin et al 2005]. The coordinates and the Euler rotation angles are the configuration parameters q.…”

Section: Mechanical Resolution By Demmentioning

confidence: 99%

Thermomechanical modelling of friction effects in granular flows using the discrete element method

Nguyen

Fortin

Guessasma

et al. 2009

J. Mech. Mater. Struct.

View full text Add to dashboard Cite

This study deals with the modelling of the thermomechanical phenomena due to friction effects during granular flow. A two-dimensional model using the discrete element method (DEM) and taking into account the contact detection and heat transfers between grains has been developed. Through this study, we have modelled the heat transfer by conductance and the energy dissipation by friction into a granular medium. This modelling enables better understanding of the phenomena at the contact point between grains as well as the energy dissipation by friction of a great number of grains in motion. The validity of the proposed model has been studied by considering some numerical simulations in quasistatic and dynamic regimes.

show abstract

“…This definition involves not only contact forces between grains, but also inertia forces in dynamical situations (see also[20] for the associated DEM simulations).…”

mentioning

confidence: 99%

Macroscopic strains in granular materials accounting for grain rotations

Kruyt

Millet

Nicot³

2014

Granular Matter

Self Cite

View full text Add to dashboard Cite

International audienceGranular materials are special materials, from the continuum-mechanical viewpoint, in the sense that they possess a clear microstructure of grains and intergrain contacts. In addition, the grains have translational as well as rotational degrees of freedom. Here a micromechanical expression is formulated for the average displacement gradient tensor in terms of the grain displacements and rotations for the two-dimensional case. It is based on a tessellation of the granular assembly into closed loops, along whose boundary the displacement field is defined in terms of the grain displacements and rotations. An important consideration for this expression is that it must satisfy the surface-additivity property, according to which the average displacement gradient of a combined two-dimensional surface is determined by the average displacement gradients of the constituent surfaces (and weighted by their areas). The developed micromechanical expression is verified by comparing its results with the macroscopic deformation as determined from the displacements at the boundary. Results of DEM simulations of a biaxial test (where the average rotation is equal to zero) and a shear test (where the average rotation is not equal to zero) are employed for this verification. The developed micromechanical expression for the displacement gradient is subsequently used to study deformation patterns in a complex case of a biaxial test where a shear band is formed

show abstract

Numerical simulation of granular materials by an improved discrete element method

Cited by 63 publications

References 19 publications

A probability density function of liftoff velocities in mixed-size wind sand flux

A probability density function of liftoff velocities in mixed-size wind sand flux

Thermomechanical modelling of friction effects in granular flows using the discrete element method

Macroscopic strains in granular materials accounting for grain rotations

Contact Info

Product

Resources

About