Discrete Element Method Simulations for Complex Granular Flows

Abstract

This review article focuses on the modeling of complex granular flows employing the discrete element method (DEM) approach. The specific topic discussed is the application of DEM models for the study of the flow behavior of nonspherical, flexible, or cohesive particles, including particle breakage. The major sources of particle cohesion—liquid induced, electrostatics, van der Waals forces—and their implementation into DEM simulations are covered. These aspects of particle flow are of great importance in practical applications and hence are the significant foci of research at the forefront of current DEM modeling efforts. For example, DEM simulations of nonspherical grains can provide particle stress information needed to develop constitutive models for continuum-based simulations of large-scale industrial processes.

Colloidal crystals and water: Perspectives on liquid–solid nanoscale phenomena in wet particulate media

“…The fact that moisture affects the mechanical response of granular materials suggests that such influence is not negligible. Powerful numerical tools for investigation of force networks and granular flows like the discrete element method have a great difficulty in assuming a distribution of the liquid, in particular, the liquid fraction forming bridges and their shape [46,172,194 ]. Since these factors are achievable in silica CCs, accurate simulations can be compared to opal mechanical performance, and, in turn, it may help refine the modeling of such aspects.…”

“…Nevertheless, most work has focused on dry particulate systems (solid-gas) [37,42,43] and, more recently, colloidal and granular suspensions (solid-liquid) [44,45] because of the much simpler binary-phase scenario −even so, they are still poorly understood. The additional fluid phase in the unsaturated case strongly complicates the picture and justifies that, apart from the phenomenology, the physics of wet particulate systems have been little studied and remains largely unknown [35,46]. One reason is that, although liquid-particles behavior relies on nanoscale phenomena, most research has been limited to relatively large scales, from millimeter down to micrometer (as in wet granular media [24,35,36,39,47]).…”

Polydisperse granular flows over inclined channels

“…However, for highly dense, quasi-static flows, where particle contacts are enduring and multiple, the soft-particle approach is, clearly, preferable. For a detailed review of these approaches, their corresponding algorithms, theoretical advances and applications we refer to recent reviews [21,51,[72][73][74] and the references therein.…”

“…Even though the majority of the references listed in these articles [21,51,[72][73][74] consider spherically shaped particles, particulate systems encountered in industry or nature are often made up of non-spherical and/or irregularly shaped particles. Studies have shown that particle geometry considerably affects the bulk dynamics of particulate mixtures.…”

“…Innovative simulations on the order of millions of particles are being conducted in quasi real-time in confined environments [60], rotating drums [61], blenders [62], granular soils [63]. This is because of the sophisticated algorithms developed for efficient collision detection [64][65][66][67][68][69][70][71] and constructing memory-efficient data structures [72]. Using high performance GPU's, [73] investigated the size effects in granular mixture flows, whereas [74] used it to simulate fractures in heterogeneous media.…”