Investigation of granular batch sedimentation via DEM–CFD coupling

Zhao, Tao; Houlsby, G. T.; Utili, Stefano

doi:10.1007/s10035-014-0534-0

Cited by 82 publications

(45 citation statements)

References 41 publications

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“…The current study considers this setting for numerical simulations by the discrete element method (DEM) (Cundall & Strack, ). The DEM has been widely employed as a tool for numerical modelling of rock avalanches and solid breakages (Boon et al, , ; Calvetti et al, ; Fu et al, ; Shen et al, ; Taboada & Estrada, ; Timár et al, ; Zhao et al, , , ). As stated by Alassi and Holt (), the method is capable of modeling complex dynamic responses of rock mass, such as crack initiation and propagation.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Fragmentation of Jointed Rock Blocks During Rockslide‐Avalanches: Insights From Discrete Element Analyses

et al. 2018

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The dynamic fragmentation of jointed rock blocks during rockslide avalanches has been investigated by discrete element method simulations for a multiple arrangement of a rock block sliding over a simple slope geometry. The rock blocks are released along an inclined sliding plane and subsequently collide onto a flat horizontal plane at a sharp kink point. The contact force chains generated by the impact appear initially at the bottom frontal corner of the rock block and then propagate radially upward to the top rear part of the block. The jointed rock blocks exhibit evident contact force concentration and discontinuity of force wave propagation near the joint, associating with high energy dissipation of granular dynamics. The corresponding force wave propagation velocity can be less than 200 m/s, which is much smaller than that of an intact rock (1,316 m/s). The concentration of contact forces at the bottom leads to high rock fragmentation intensity and momentum boosts, facilitating the spreading of many fine fragments to the distal ends. However, the upper rock block exhibits very low rock fragmentation intensity but high energy dissipation due to intensive friction and damping, resulting in the deposition of large fragments near the slope toe. The size and shape of large fragments are closely related to the orientation and distribution of the block joints. The cumulative fragment size distribution can be well fitted by the Weibull's distribution function, with very gentle and steep curvatures at the fine and coarse size ranges, respectively. The numerical results of fragment size distribution can match well some experimental and field observations.

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Section: Introductionmentioning

confidence: 99%

Dynamic Fragmentation of Jointed Rock Blocks During Rockslide‐Avalanches: Insights From Discrete Element Analyses

et al. 2018

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“…The final settling velocity could be measured and compared with an available analytical solution. The results show good comparability between the CFD-DEM simulation and analytical solution [20,22]. Consequently, validation will not be further discussed in this paper.…”

Section: Valiadationmentioning

confidence: 86%

“…The validity of the above drag force expression has been investigated by many researchers [19][20][21], who have indicated that this expression works well in flow systems with relatively low Reynolds numbers.…”

Section: Governing Equations Of Cfd and Fluid-particle Intercationmentioning

confidence: 99%

A Coupled CFD–DEM Simulation of Slurry Infiltration and Filter Cake Formation during Slurry Shield Tunneling

Zhang

Yin

2018

Infrastructures

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Tunneling in highly permeable ground using a slurry shield machine can be challenging because it is difficult to form the so-called filter cake on the tunnel face to transport the support pressure. Consequently, destructive accidents might happen, such as face instability and water inrush. How to form an efficient filter cake in time is crucial during engineering practice, especially in ground with high permeability. Various theoretical and experimental analyses regarding the formation of filter cakes have been conducted. However, due to the complexity of this problem, which has to incorporate the mechanical and hydraulic behaviors of the fluid-solid mixture system, few numerical simulations are found in the literature. In this paper, with the aid of a newly developed numerical tool, a coupled CFD (computational fluid dynamics)-DEM (discrete element method) simulation is established to study the slurry infiltration and filter cake formation during slurry shield tunneling. The slurry infiltration process is simulated by modelling the scheme of the infiltration column test, in which sedimentation behaviors of slurry particles are captured and compared with experimental results. The results show that the sedimentation behaviors of the slurry particles and filter cake formation phenomenon are well captured by simulations and in accordance with the experiments, which indicates the robustness of the coupled CFD-DEM simulation used in present work.

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“…Therefore, the understanding of the settling process is important in the calculation of sediment budget for engineering, economic and environmental reasons. In addition, the sedimentation process is found in chemical, mining, pharmaceutical and other industries due to its importance in the understanding of fluid-solid separation (Shih et al, 1987;Bürger and Wendland, 2001;Dong et al, 2009;Zhao et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…The modeling of the silt settling process is hindered by the complex dynamics of the particles and the challenges in predicting the fluid-particle interaction and inter-particle contact. The traditional empirical approaches based on experimental measurements (Richardson and Zaki, 1954;Winterwerp and van Kesteren, 2004;te Slaa et al, 2015) are used to predict the settling velocity, which is among the most important quantities of interest for the fluid-solid mixture (Batchelor and Green, 1972;Hinch, 1977;Zhao et al, 2014). At higher particle concentrations, the influence of return flow and wake formation, the inter-particle collision, and the increased buoyancy effects are considered in the settling process (Winterwerp, 2002).…”

Section: Introductionmentioning

confidence: 99%

Investigating the settling dynamics of cohesive silt particles with particle-resolving simulations

Sun

Xiao

Sun

2018

Advances in Water Resources

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The settling of cohesive sediment is ubiquitous in aquatic environments, and the study of the settling process is important for both engineering and environmental reasons. In the settling process, the silt particles show behaviors that are different from non-cohesive particles due to the influence of inter-particle cohesive force. For instance, the flocs formed in the settling process of cohesive silt can loosen the packing, and thus the structural densities of cohesive silt beds are much smaller than that of non-cohesive sand beds. While it is a consensus that cohesive behaviors depend on the characteristics of sediment particles (e.g., Bond number, particle size distribution), little is known about the exact influence of these characteristics on the cohesive behaviors. In addition, since the cohesive behaviors of the silt are caused by the inter-particle cohesive forces, the motions of and the contacts among silt particles should be resolved to study these cohesive behaviors in the settling process. However, studies of the cohesive behaviors of silt particles in the settling process based on particle-resolving approach are still lacking. In the present work, three-dimensional settling process is investigated numerically by using CFD-DEM (Computational Fluid Dynamics-Discrete Element Method). The inter-particle collision force, the van der Waals force, and the fluid-particle interaction forces are considered. The numerical model is used to simulate the hindered settling process of silt based on the experimental setup in the literature. The results obtained in the simulations, including the structural densities of the beds, the characteristic lines, and the particle terminal velocity, are in good agreement with the experimental observations in the literature. To the authors' knowledge, this is the first time that the influences of non-dimensional Bond number and particle polydispersity on the structural densities of silt beds have been investigated separately. The results demonstrate that the cohesive behavior of silt in the settling process is attributed to both the cohesion among silt particles themselves and the particle polydispersity. To guide to the macro-scale modeling of cohesive silt sedimentation, the collision frequency functions obtained in the numerical simulations are also presented based on the micromechanics of particles. The results obtained by using CFD-DEM indicate that the binary collision theory over-estimated the particle collision frequency in the flocculation process at high solid volume fraction.

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Investigation of granular batch sedimentation via DEM–CFD coupling

Cited by 82 publications

References 41 publications

Dynamic Fragmentation of Jointed Rock Blocks During Rockslide‐Avalanches: Insights From Discrete Element Analyses

Dynamic Fragmentation of Jointed Rock Blocks During Rockslide‐Avalanches: Insights From Discrete Element Analyses

A Coupled CFD–DEM Simulation of Slurry Infiltration and Filter Cake Formation during Slurry Shield Tunneling

Investigating the settling dynamics of cohesive silt particles with particle-resolving simulations

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