Granular materials composed of shape-anisotropic grains

Börzsönyi, Tamás; Stannarius, Ralf

doi:10.1039/c3sm50298h

Cited by 133 publications

(103 citation statements)

References 168 publications

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“…Due to dynamics in continuous shearing, this ordering phenomenon emerges even in systems composed of particles with very low platyness with a shape differing only slightly from spherical shape. This kind of ordering has previously been observed in experiments [27,22] and numerical simulations mainly with two-dimensional elongated particles [28,15,18]. Regarding the privileged direction of alignment, we found that, as platyness increases, this direction gradually changes from that of the major principal stress to a direction that is perpendicular to the shear direction.…”

Section: Summary and Discussionsupporting

confidence: 49%

“…This evolution of the privileged direction of alignment is consistent with several observations reported in Refs. [28,27,22].…”

Section: Summary and Discussionmentioning

confidence: 99%

“…More generally, packings composed of shape-anisotropic particles (i.e. elongated/prolate or flattened/oblate) have attracted increasing interest in recent years [22]. Oblate particles prefer facing along the major principal stress direction with the flat side, while prolate particles prefer orientation of their long axis along the minor principal stress direction [23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

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Particle alignment and clustering in sheared granular materials composed of platy particles

Boton¹,

Estrada²,

Azéma³

et al. 2014

Eur. Phys. J. E

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Abstract. By means of molecular dynamics simulations, we investigate the texture and local ordering in sheared packings composed of cohesionless platy particles. The morphology of large packings of platy particles in quasistatic equilibrium is complex due to the combined effects of local nematic ordering of the particles and anisotropic orientations of contacts between particles. We find that particle alignment is strongly enhanced by the degree of platyness and leads to the formation of face-connected clusters of exponentially decaying size. Interestingly, due to dynamics in continuous shearing, this ordering phenomenon emerges even in systems composed of particles of very low platyness differing only slightly from spherical shape. The number of clusters is an increasing function of platyness. However, at high platyness the proportion of face-face interactions is too low to allow for their percolation throughout the system. PACS. PACS-key discribing text of that key -PACS-key discribing text of that key

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Section: Summary and Discussionsupporting

confidence: 49%

“…This evolution of the privileged direction of alignment is consistent with several observations reported in Refs. [28,27,22].…”

Section: Summary and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Particle alignment and clustering in sheared granular materials composed of platy particles

Boton¹,

Estrada²,

Azéma³

et al. 2014

Eur. Phys. J. E

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“…The behaviour of a single elongated free flowing intruder within a 2D layer of spheres has also been studied [7]. The elongation of particles in particular introduces many complexities such as the change in jamming transition, altering of shear strength parameters, the orientation of these particles with the principal stress region within sheared assemblies, and the strong dependence on initial conditions [5]. There exist no adequate models to explain these additional factors which are introduced into the rheology of granular materials by anisotropic shaped particles -even for relatively simple shapes such as ellipsoids or rods [5].…”

Section: Introductionmentioning

confidence: 99%

“…Many tests, both experimental and computational, have used spheres or cylinders due to the simplicity of those shapes [1] with glass beads often chosen for fundamental experiments. There have been studies conducted on systems entirely consisting of irregularly shaped or elongated particles [2][3][4][5], as well as the influence of mixtures of regular and elongated particles [6]. The behaviour of a single elongated free flowing intruder within a 2D layer of spheres has also been studied [7].…”

Section: Introductionmentioning

confidence: 99%

The behaviour of free-flowing granular intruders

et al. 2017

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Abstract. Particle shape affects both the quasi-static and dynamic behaviour of granular media. There has been significant research devoted to the flowability of systems of irregularly shaped particles, as well as the flow of grains around fixed intruders, however the behaviour of free flowing intruders within granular flows remains comparatively unexplored. Here, the effect of the shape of these intruder particles is studied, looking at the kinematic behaviour of the intruders and in particular their tendency of orientation. Experiments are carried out within the Stadium Shear Device, which is a novel apparatus able to continuously apply simple shear conditions to two-dimensional grain analogues. It is found that the intruder shows different behaviour to that of the bulk flow, and that this behaviour is strongly shape dependent. These insights could lead to the development of admixtures that alter the flowability of granular materials.

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On the kinematics and dynamics of crystal‐rich systems

2017

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Partially molten rocks, often called a mush, are examples of a hydrogranular mixture where the dynamics are controlled by both fluid and crystal‐crystal interactions. An obstacle to progress in understanding high‐temperature hydrogranular systems has been the lack of adequate levels of description of microphysical processes. Here we rationalize the hydrogranular kinematic and dynamic states by applying the concept of particle (crystal) force chains. We exemplify this with discrete‐element computational fluid dynamic simulations of the intrusion of a basaltic melt into an olivine‐basalt mush, where crystal‐scale force chains, crystal transport, and melt mixing are resolved. To describe the microscale kinematics of the system, we introduce the coordination number and the fabric tensors of particle contacts and forces. We quantify the changing contact and force fabric anisotropy, coaxiality, and the connectedness of the mush, under dynamic conditions. To describe the dynamics, particle and fluid characteristic response times are derived. These are used to define local and bulk Stokes numbers, and viscous and inertia numbers, which quantify the multiphase coupling under crystal‐rich conditions. We employ the Sommerfeld number, which describes the importance of crystal‐melt lubrication, with a viscous number to illustrate the dynamic regimes of crystal‐rich magmas. We show that the notion of mechanical “lock up” is not uniquely identified with a particular crystal volume fraction and that distinct mechanical behaviors can emerge simultaneously within a crystal‐rich system. We also posit that this framework describes magmatic fabrics and processes which “unlock” a crystal mush prior to eruption or mixing.

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Granular materials composed of shape-anisotropic grains

Cited by 133 publications

References 168 publications

Particle alignment and clustering in sheared granular materials composed of platy particles

Particle alignment and clustering in sheared granular materials composed of platy particles

The behaviour of free-flowing granular intruders

On the kinematics and dynamics of crystal‐rich systems

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