Article
Engineering, Chemical
Jens H. Kasper, Vanessa Magnanimo, Sjoerd D. M. de Jong, Arjan Beek, Ahmed Jarray
Summary: This study investigated the effects of liquid viscosity and particle size on the dynamics of wet granular material using a discrete element method (DEM) model. It found that as liquid viscosity increases, avalanche amplitude, flow layer velocity, and granular temperature decrease, especially for smaller sized particles. The increase in viscous forces causes the flowing particles to behave as a bulk, pushing the free surface towards a convex shape, and leads to a transition from avalanching to continuous granular flow.
Article
Energy & Fuels
Camilo Pedrosa, Arild Saasen, Jan David Ytrehus
Summary: The formation of cuttings-beds is a crucial consideration during wellbore drilling operations, especially in highly deviated or horizontal wells. This study analyzes the bonding strength and stress required to break the formed bed of wetted cuttings using granular rheology methodology. The results show that the composition of the interstitial fluid significantly impacts the shear strength of the bed, with water-based drilling fluid exhibiting higher cohesion compared to oil-based drilling fluids.
GEOENERGY SCIENCE AND ENGINEERING
(2023)
Article
Engineering, Chemical
Olumide Ogunmodimu, Indresan Govender, Aubrey Njema Mainza, Jean-Paul Franzidis
Summary: Screening is commonly used to separate granulated ore materials into different particle sizes, with optimal efficiency in screen performance becoming crucial for downstream processing. Various techniques have been employed to study granular flow on vibrating screens, but further advancement in modeling requires a mechanistic understanding of particle motion on the screen. A concept of granular rheology is applied in this study to overcome dependence on empirical models, with a visco-plastic model developed to describe granular flow on an inclined vibratory screen. The model captures the flow transition from quasi-static to dense-flow regimes, providing insights for different vibrational frequencies.
MINERALS ENGINEERING
(2021)
Article
Engineering, Chemical
Marv J. Khala, Colin Hare, Chuan-Yu Wu, Navin Venugopal, Martin J. Murtagh, Tim Freeman
Summary: The rheological behavior of a dense granular bed under dynamic conditions is investigated using the Discrete Element Method. The distribution of stresses and strain rates in the bed, as well as their dependence on material properties and blade operational conditions, are analyzed. The study proposes a predictive model for computing the average shear stress in the granular bed based on blade torque, considering the effects of blade tip speed, particle aspect ratio, and interfacial energy.
Article
Engineering, Chemical
T. M. Povall, I Govender, A. T. McBride
Summary: A novel 3D measurement method was proposed to test the compressibility and isotropy of rotating drum flows using the DEM with mu(I) rheology. The study found that compressibility enhances isotropy and statistically better fits were obtained when using an empirically-derived friction law. However, all models failed to capture behavior at very low inertial numbers.
Article
Engineering, Chemical
M. Mouzaoui, M. Sauceau, L. Devriendt, J. C. Baudez, P. Arlabosse
Summary: The study investigates the impact of structural changes during sludge treatments on flowability and technical issues using different experimental methods. Results show a transition from pasty to granular-like material at 43 wt% TS content. Sludge exhibits powder-like behavior with increasing frictional interactions, especially above 43 wt% TS content.
Article
Computer Science, Interdisciplinary Applications
Jianqiu Tian, Yuanming Lai, Enlong Liu, Chuan He
Summary: A micro-macro elastoplastic micropolar continuum model for granular materials is proposed, which takes into account both translational and rotational degrees of freedom. The model parameters have clear physical meanings and the stress-strain relation and strain localization phenomenon can be accurately predicted. The proposed model is validated using ABAQUS software and shows good agreement with experimental and simulation results.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Mechanics
S. Deboeuf, A. Fall
Summary: Multi-phase flows have complex rheological properties, which can be better understood through the use of model materials and appropriate rheometers. Our study focused on unsaturated wet granular flows down a rough inclined plane and found that they exhibit steady and uniform behavior over a wide range of parameters, despite cohesion and grain aggregates. By extending the cohesive Mohr-Coulomb yield criterion to inertial granular flows, with cohesion stress dependent on liquid content and an internal friction coefficient dependent on inertial number, we were able to make predictions that matched well with experimental measurements. The introduction of a grain aggregate size, which defines appropriate length and relaxation time scales in the inertial number, was necessary for accurate predictions.
JOURNAL OF RHEOLOGY
(2023)
Article
Computer Science, Interdisciplinary Applications
N. Younes, A. Wautier, R. Wan, O. Millet, F. Nicot, R. Bouchard
Summary: In this paper, a phase-field-based Lattice Boltzmann Method (LBM) model coupled with the Discrete Element Method (DEM) is proposed to simulate unsaturated granular media. The LBM scheme is used to compute the formation of capillary bridges between grains, while the DEM computes the motions of the grains. An efficient DEM-LBM coupling framework is used to explore capillarity effects at the pore scale. The proposed coupling scheme becomes a viable numerical tool to model and explore pore-scale phenomena in unsaturated soils.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Geochemistry & Geophysics
N. Casas, G. Mollon, A. Daouadji
Summary: Fault zones are composed of granular gouge, which contributes to friction stability. Different infill materials can be observed in mature fault zones, changing the rheological and frictional behaviors of the gouge. The study aims to understand the influence of grain-scale characteristics on slip mechanisms and gouge rheology by using the discrete element method. The findings suggest that gouge materials with high interparticle friction or high shear modulus may lead to faster earthquake ruptures.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Engineering, Chemical
Lixiang Zhong, Dandan Xu, Yiyang Jiang, Yu Guo
Summary: Gas-fluidized beds of wet flexible fibers are investigated using a coupled approach of Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD). The effects of cohesion and fiber flexibility on fluidization characteristics are examined. It is found that cohesion and fiber flexibility affect the pressure drop, minimum fluidization velocity, and solids mixing rate.
Article
Engineering, Geological
Pawan Kumar Soni, Arun K. Singh, N. Sivakumar, Trilok N. Singh
Summary: This article experimentally studies the frictional properties of a wet granular layer on a rock surface and explores the relationship between the static, steady, and residual stresses of the wet layer and the shear rate. The adhesive stress and coefficient of friction are determined using Coulomb's law of friction, and it is found that both components of friction increase with shear rate. A friction model is used to predict the static friction of the granular layer, and scaling laws are proposed for static friction in terms of chain density, relaxation time, and extension of molecular chains.
INTERNATIONAL JOURNAL OF GEOMECHANICS
(2022)
Article
Engineering, Chemical
Mingrui Dong, Zhongzheng Wang, Yixiang Gan
Summary: This study adopts the discrete element method (DEM) to propose a strategy for tailoring packing structures by controlling the cohesive forces between particles. By comparing the results with previous experiments, the effectiveness of this strategy is demonstrated, and it is found that larger clusters tend to form looser packing structures. The study also reveals that the effect of cohesion varies throughout different stages of packing, which sheds light on the understanding of wet granular packing.
Article
Physics, Fluids & Plasmas
James A. Robinson, Daniel J. Holland, Luke Fullard
Summary: Recent research has used granular fluidity to model nonlocal behavior within granular flows, proposing a microscopic definition linking it to packing fraction, particle diameter, and granular temperature. The study found that granular fluidity is more complex than previously thought, and the current microscopic definition is insufficient to capture its behavior.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Engineering, Geological
Wei Xiong, Jianfeng Wang, Zhuang Cheng
Summary: This paper investigates the capability of discrete element method (DEM) with realistic particle morphology for modelling granular soils' micro-macro mechanical responses. The results show that DEM with realistic particle morphology can reasonably reproduce granular materials' mechanical behaviours. Moreover, the role of multiscale particle morphology in granular soils depends on the initial packing state and the confining stress condition.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Editorial Material
Materials Science, Multidisciplinary
Diego Berzi, Dalila Vescovi, Shunying Ji, Xikui Li, Stefan Luding
Article
Engineering, Chemical
J. E. Alvarez, H. Snijder, T. Vaneker, H. Cheng, A. R. Thornton, S. Luding, T. Weinhart
Summary: This study presents a novel discrete element method framework for modeling the visco-elastic sintering kinetics in polymer powders. The framework considers three distinct sintering mechanisms and is implemented in an open-source software package. Experimental data analysis confirms the accuracy of the sintering time estimation compared to a widely-used model. This research provides an efficient and reliable approach for studying strength evolution in powder-bed fusion processes.
Article
Physics, Fluids & Plasmas
Abhinendra Singh, Grayson L. Jackson, Michael van der Naald, Juan J. de Pablo, Heinrich M. Jaeger
Summary: When dispersing small particles in a liquid, surprising behaviors can occur when the solids fraction is large. Researchers have shown through simulations that focusing on constraints related to sliding and rolling can quantitatively reproduce the observed shear thickening behavior, regardless of particle properties, surface chemistries, and suspending fluids.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Physics, Multidisciplinary
Mohammad Nabizadeh, Abhinendra Singh, Safa Jamali
Summary: This study compares force network formation in continuous and discontinuous shear thickening dense suspensions, revealing notable differences in their characteristics and impact on system behavior.
PHYSICAL REVIEW LETTERS
(2022)
Article
Engineering, Multidisciplinary
Hongyang Cheng, Anthony R. Thornton, Stefan Luding, Andrew L. Hazel, Thomas Weinhart
Summary: The finite element method (FEM) is commonly used for modeling continuum media, while the discrete element method (DEM) is used for discrete systems. This paper introduces the coupling between discrete and continuum methods by mapping discrete particle data onto smooth fields. The authors found that using this coarse-graining approach leads to more accurate results, reduced energy generation, and less numerical dissipation.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2023)
Article
Chemistry, Physical
Thejas Hulikal Chakrapani, Hanieh Bazyar, Rob G. H. Lammertink, Stefan Luding, Wouter K. den Otter
Summary: Darcy's law describes the flow of Newtonian fluids through porous media, while Brinkman extended it by adding a viscous stress term. The validity and value of Brinkman's term have been debated since its introduction.
Article
Multidisciplinary Sciences
K. Taghizadeh, M. Ruf, S. Luding, H. Steeb
Summary: This research focuses on performing ultrasound propagation measurements and micro-X-ray computed tomography imaging on prestressed granular packings prepared with biphasic mixtures of monodisperse glass and rubber particles at different compositions/fractions. The study reveals that the effective macroscopic stiffness of the granular packings transits nonlinearly and nonmonotonically toward the soft limit as the fraction of soft particles increases. The contact network of dense packings plays a key role in understanding this phenomenon.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Materials Science, Multidisciplinary
Sudeshna Roy, Mohamad Yousef Shaheen, Thorsten Poeschel
Summary: Producing consistent layer quality for different raw materials in powder-based additive manufacturing is a challenge. The role of interparticle cohesion on powder spreading process is characterized through numerical simulations using the discrete element method in this study. The effect of particle cohesion on powder layer quality is evaluated, revealing that higher interparticle cohesion leads to poor spreadability, more heterogeneous powder layer structure, and enhanced particle size segregation. The quality of powder layer deposited on a smooth substrate is compared with that on a powder layer, showing that deposition on a powder layer results in inferior layer quality with higher heterogeneity and particle size segregation effects.
Article
Polymer Science
Kathryn G. Wilcox, Alexandra Grinevich, Adam Linscott, Abhinendra Singh, Svetlana Morozova
Summary: This study investigates the mechanical properties of poly-(l)-lysine (PLL) hydrogels, whose network chains undergo a random coil-helix transition. It is found that the conformation change has a significant effect on the nonlinear mechanical properties of PLL hydrogels. At low cross-link percents, a transition from strain softening to strain hardening is observed as the network chains become helical. However, at higher cross-link densities, the hydrogels become brittle due to stress concentration in inhomogeneous locations in the network.
MACROMOLECULAR CHEMISTRY AND PHYSICS
(2023)
Article
Chemistry, Physical
Abhinendra Singh, Kuniyasu Saitoh
Summary: Dense suspensions exhibit significant response to external deformation, which is related to the transition from lubrication to frictional state. Numerical simulations in two dimensions show that the viscosity and diffusivity of frictional non-Brownian spheres increase under characteristic shear stress. A one-to-one relationship between viscosity and diffusivity is proposed, using the length scale associated with collective motions of particles. The power laws describing the relationship between viscosity, diffusivity, and shear stress are insensitive to interparticle friction and system size.
Article
Engineering, Mechanical
Hongyang Cheng, Stefan Luding, Thomas Weinhart
Summary: The interaction between granular materials and deformable structures is important in various industries. A surface coupling method combining discrete and continuum methods is commonly used for numerical modeling. This study investigates the time evolution of linear momenta and energies in particle-continuum systems using a recently developed coarse graining method, and shows that it leads to more accurate predictions and reduces excess energies generated by the coupling method, particularly in dynamic particle-structure interactions.
ACTA MECHANICA SINICA
(2023)
Article
Physics, Fluids & Plasmas
D. Hernandez-Delfin, D. R. Tunuguntla, T. Weinhart, R. C. Hidalgo, A. R. Thornton
Summary: This study reveals the segregation mechanisms of granular mixtures with different shapes under shear. Two distinct segregation mechanisms driven by relative overstress are identified, and a competition between kinetic and gravity effects is observed for nonspherical particles.
Article
Physics, Fluids & Plasmas
Juan C. Petit, Nishant Kumar, Stefan Luding, Matthias Sperl
Summary: This study presents three-dimensional simulations of bidisperse granular packings using the discrete element method. The results show the existence of two jamming transitions, with the first one predominantly involving large particles and the second one involving small-large interactions. The effective transition densities are reduced when only nonrattlers are considered. The size ratio and concentration of small particles affect the behavior of the bulk modulus during the transitions. The findings provide insights for tuning or switching the bulk modulus and other properties of granular packings.
Article
Chemistry, Physical
D. Hernandez-Delfin, T. Weinhart, R. C. Hidalgo
Summary: This work numerically studies the self-diffusion of spherocylindrical particles flowing down an inclined plane using the discrete element method (DEM). The study finds spatial regions where the diffusivity strongly correlates with the local shear rate and proposes a scaling law between the diffusion coefficient and shear rate. Specific locations where the diffusivity does not correlate with the shear rate are also identified.