Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
4.7
3.5
Journals
Processes
Special Issues
DEM Simulations and Modelling of Granular Materials
share announcement

DEM Simulations and Modelling of Granular Materials

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Materials Processes".

Deadline for manuscript submissions: closed (10 May 2022) | Viewed by 66157

Special Issue Editor

Dr. Joanna Wiącek

E-Mail Website
Guest Editor
Bohdan Dobrzański Institute of Agrophysics, Polish Academy of Sciences, Lublin, Poland
Interests: granular plant materials; mechanics of granular materials; agglomeration; biomass; numerical simulations; discrete element method

Special Issue Information

Dear Colleagues,

The increase in the scale of processing in the second half of 20th century resulted in an extensive of use of materials in granular form that was easier to handle via large-scale technologies. It has been estimated that over 75% of raw materials that pass through industry are granular in nature. These include pharmaceutical powders and tablets, pellets, agricultural grains and food products, coals and other minerals, sands, and gravels. Many of these solids display difficult handling behaviors, giving rise to considerable challenges in the design and operation of the handling and processing plants. The scientific insight into mechanical behavior of granular materials is required to apply the most efficient conveying, handling, and processing systems. These industrial applications require understanding of phenomena occurring in the granular materials and more accurate recognition of the influence of the mechanical properties on these processes.

For many years, experimental methods have been used to study the properties of granular materials. The development of computational techniques allows for a more detailed analysis of the influence of bedding structure, the generation method, and microstructural properties of grains on the mechanical response of material during filling and discharge of silo, handling, and conveying. One of the approaches to model granular mechanics problems is the discrete element method (DEM) in which the dynamics of each particle is computed with particle interactions modeled at various levels of complexity and rigor. The application of the discrete element method to model processes occurring in the granular materials provides new insights into the mechanics of these materials. 

This Special Issue on “DEM Simulations and Modelling of Granular Materials” aims to present results of DEM modeling of processes involving granular materials. Manuscripts presenting the results of the numerical simulations for the different types of materials in granular form, including plant and mineral materials, are welcomed.

Dr. Joanna Wiącek
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (25 papers)

Download All Papers
Order results
Result details
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:

Research

Jump to: Review

27 pages, 2182 KiB  
Article
Efficient Discrete Element Modeling of Particle Dampers
by Fabio Biondani, Marco Morandini, Gian Luca Ghiringhelli, Mauro Terraneo and Potito Cordisco
Processes 2022, 10(7), 1247; https://doi.org/10.3390/pr10071247 - 22 Jun 2022
Cited by 5 | Viewed by 2123
Abstract
Particle dampers’ dissipative characteristics can be difficult to predict because of their highly non-linear behavior. The application of such devices in deformable vibrating systems can require extensive experimental and numerical analyses; therefore, improving the efficiency when simulating particle dampers would help in this [...] Read more.
Particle dampers’ dissipative characteristics can be difficult to predict because of their highly non-linear behavior. The application of such devices in deformable vibrating systems can require extensive experimental and numerical analyses; therefore, improving the efficiency when simulating particle dampers would help in this regard. Two techniques often proposed to speed up the simulation, namely the adoption of a simplified frictional moment and the reduction of the contact stiffness, are considered; their effect on the simulation run-time, on the ability of the particle bed to sustain shear deformation, and on the prediction of the dissipation performance is investigated for different numerical case studies. The reduction in contact stiffness is studied in relation to the maximum overlap between particles, as well as the contacts’ duration. These numerical simulations are carried out over a wide range of motion regimes, frequencies, and amplitude levels. Experimental results are considered as well. All the simulations are performed using a GPU-based discrete element simulation tool coupled with the multi-body code MBDyn; the results and execution time are compared with those of other solvers. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

13 pages, 1701 KiB  
Article
Calibration and Experimental Validation of Contact Parameters in a Discrete Element Model for Tobacco Strips
by Wei Jiang, Lihua Wang, Jun Tang, Yanchao Yin, Hao Zhang, Tongpeng Jia, Jiwei Qin, Huaiyu Wang and Qike Wei
Processes 2022, 10(5), 998; https://doi.org/10.3390/pr10050998 - 18 May 2022
Cited by 5 | Viewed by 1879
Abstract
To study the contact parameters of the tobacco strips during redrying, in this study, the funnel stacking test is used to determine the stacking angle, and the discrete element method is used to simulate the formation process of the stacking angle, to calibrate [...] Read more.
To study the contact parameters of the tobacco strips during redrying, in this study, the funnel stacking test is used to determine the stacking angle, and the discrete element method is used to simulate the formation process of the stacking angle, to calibrate and verify the physical and contact parameters of tobacco strips. The Placket–Burman test was used to screen out the parameters that had significant effects on the stacking angle. The regression response surface model between the stacking angle and contact parameters was established by Central Composite Design using the stacking angle from physical tests as the response index. The test results show that static and rolling friction coefficients between tobacco strips have significant effects on the test results, so these two parameters must be accurately calibrated. Finally, the accuracy and validity of the calibrated tobacco strips contact parameters were verified by comparing the stacking angle and void ratio of physical and simulation experiments. The calibration results can provide basic parameters for studying the interaction and motion of the tobacco strips in the redrying process using simulation methods. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

16 pages, 6951 KiB  
Article
Investigation on Creep Behavior of Aggregates of Loess by a Discrete Element Method
by Jian-Qiang Sun, Xi-An Li, Mei-Le Bi, Kai-Xuan Zhang and Jing Zhang
Processes 2022, 10(4), 795; https://doi.org/10.3390/pr10040795 - 18 Apr 2022
Viewed by 1529
Abstract
In loess the aggregate is the basic structural unit, and its stability is an important factor affecting the composition, water stability and strength of loess. However, due to the difficulty of sample preparation, few scholars have done independent research on it. In this [...] Read more.
In loess the aggregate is the basic structural unit, and its stability is an important factor affecting the composition, water stability and strength of loess. However, due to the difficulty of sample preparation, few scholars have done independent research on it. In this manuscript, a numerical model of aggregate is constructed by the discrete element method. Under the continuous action of certain stress, the uninterrupted development process of sample deformation with time was observed, that is, the creep of aggregate structures. The results show that the creep of aggregates is closely related to the relative movement, rotation and rearrangement of internal structural elements, and the most intuitive mesoscopic evolution of the adjustment process of structural elements is the change of contact number, namely the coordination number. The microscopic parameters and evolutionary characteristics of fabric can reveal the microscopic mechanism behind the macroscopic creep phenomenon. With the creep process, the creep stress is gradually borne by the normal contact force rather than the tangential contact force and has anisotropic characteristics. As a result of creep, the contact points of particles increase, and the interaction between aggregates changes from point contact to overlap contact. The constraint between aggregates increases, and the skeleton tends to be a more stable structure, which can bear a larger load. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

15 pages, 1030 KiB  
Article
A Numerical Research on the Relationship between Aeolian Sand Ripples and the Sand Flux
by Xinghui Huo, Ning Huang and Jie Zhang
Processes 2022, 10(2), 354; https://doi.org/10.3390/pr10020354 - 12 Feb 2022
Cited by 2 | Viewed by 1505
Abstract
Theoretically, the sand flux will not change after the wind-driven sand particle transport reaches the saturated state. However, it has been found in many wind-tunnel experiments that the sand flux will gradually decrease with time in long-term particle transport duration and will eventually [...] Read more.
Theoretically, the sand flux will not change after the wind-driven sand particle transport reaches the saturated state. However, it has been found in many wind-tunnel experiments that the sand flux will gradually decrease with time in long-term particle transport duration and will eventually reach a new stable state. In this work, we used numerical simulations to study the source of this kind of decrease and found it is caused by the sand ripple on the bed surface. The ripple index showed a strong correlation to the sand flux, and it decreased during the initial stage of the ripple formation. With a simplified theoretical model, we found the linear relationship between the Shields number and the particle transport load holds. However, the slope of this relationship and the dynamic threshold of particle entrainment decreased with the ripple index. As the sand flux scales linearly with the particle transport load, we finally derived an expression that describes how the sand flux on the ripple bedform varies with the wind strength. From this expression, we found the sand flux increases with ripple index, and it was easier to be influenced by the ripple bed form in small wind strength. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

13 pages, 22032 KiB  
Article
Load-Balancing Strategies in Discrete Element Method Simulations
by Shahab Golshan and Bruno Blais
Processes 2022, 10(1), 79; https://doi.org/10.3390/pr10010079 - 31 Dec 2021
Cited by 3 | Viewed by 1995
Abstract
In this research, we investigate the influence of a load-balancing strategy and parametrization on the speed-up of discrete element method simulations using Lethe-DEM. Lethe-DEM is an open-source DEM code which uses a cell-based load-balancing strategy. We compare the computational performance of different cell-weighing [...] Read more.
In this research, we investigate the influence of a load-balancing strategy and parametrization on the speed-up of discrete element method simulations using Lethe-DEM. Lethe-DEM is an open-source DEM code which uses a cell-based load-balancing strategy. We compare the computational performance of different cell-weighing strategies based on the number of particles per cell (linear and quadratic). We observe two minimums for particle to cell weights (at 3, 40 for quadratic, and 15, 50 for linear) in both linear and quadratic strategies. The first and second minimums are attributed to the suitable distribution of cell-based and particle-based functions, respectively. We use four benchmark simulations (packing, rotating drum, silo, and V blender) to investigate the computational performances of different load-balancing schemes (namely, single-step, frequent and dynamic). These benchmarks are chosen to demonstrate different scenarios that may occur in a DEM simulation. In a large-scale rotating drum simulation, which shows the systems in which particles occupy a constant region after reaching steady-state, single-step load-balancing shows the best performance. In a silo and V blender, where particles move in one direction or have a reciprocating motion, frequent and dynamic schemes are preferred. We propose an automatic load-balancing scheme (dynamic) that finds the best load-balancing steps according to the imbalance of computational load between the processes. Furthermore, we show the high computational performance of Lethe-DEM in the simulation of the packing of 108 particles on 4800 processes. We show that simulations with optimum load-balancing need ≈40% less time compared to the simulations with no load-balancing. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

13 pages, 2752 KiB  
Article
Discrete Element Simulation on Sand-Bed Collision Considering Surface Moisture Content
by Hongchao Dun, Peng Yue, Ning Huang and Jie Zhang
Processes 2022, 10(1), 52; https://doi.org/10.3390/pr10010052 - 28 Dec 2021
Cited by 6 | Viewed by 1966
Abstract
The process of aeolian sand transport is an important mechanism leading to the formation and evolution of local landforms in coastal areas and desert lakes. For a long time, the role of surface moisture in incipient motion of sand grains by wind stress [...] Read more.
The process of aeolian sand transport is an important mechanism leading to the formation and evolution of local landforms in coastal areas and desert lakes. For a long time, the role of surface moisture in incipient motion of sand grains by wind stress has been extensively studied but, in fact, sand-bed collision is the main mechanism in steady aeolian sand flow. At present, the lack of understanding of surface moisture content on sand-bed collision limits the application of aeolian sand transport models in wet coastal areas. In this paper, we adopt numerical simulations to discuss and analyze the effect of cohesive forces formed by surface moisture content on the sand-bed collision process based on discrete element method. High density contact forces appear with the surface moisture increasing, and form a closed structure around the edge of crater to resist the avulsion in horizontal direction. Under high moisture condition, even though the ejected sand grains saltate away from the surface, the tension forces will prevent from leaving. The ejected number trend with incident velocity shows some nonlinear characteristics due to the unequally distributed force chains and liquid bridges in the unsaturated sand bed surface. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

16 pages, 13948 KiB  
Article
Experimental and Numerical Analysis on Mesoscale Mechanical Behavior of Coarse Aggregates in the Asphalt Mixture during Gyratory Compaction
by De Zhang, Zhiqiang Cheng, Dajiang Geng, Shengjia Xie and Tao Wang
Processes 2022, 10(1), 47; https://doi.org/10.3390/pr10010047 - 27 Dec 2021
Cited by 19 | Viewed by 2733
Abstract
Compaction is a critical step in asphalt pavement construction. The objective of this study is to analyze the mesoscale mechanical behaviors of coarse aggregates in asphalt mixtures during gyratory compaction through experiments and numerical simulation using the Discrete Element Method (DEM). A novel [...] Read more.
Compaction is a critical step in asphalt pavement construction. The objective of this study is to analyze the mesoscale mechanical behaviors of coarse aggregates in asphalt mixtures during gyratory compaction through experiments and numerical simulation using the Discrete Element Method (DEM). A novel granular sensor (SmartRock) was embedded in an asphalt mixture specimen to collect compaction response data, including acceleration, stress, rotation angle and temperature. Moreover, the irregularly shaped coarse aggregates were regenerated in the DEM model, and numerical simulations were conducted to analyze the evolution of aggregate interaction characteristics. The findings are as follows: (1) the measured contact stress between particles changes periodically during gyratory compaction, and the amplitude of stress tends to be stable with the increase of compaction cycles; (2) the contact stress of particles is influenced by the shape of aggregates: flat-shaped particles are subjected to greater stress than angular, fractured or elongated particles; (3) the proportion of strong contacts among particles is high in the initial gyratory compaction stage, then decreases as the number of gyratory compactions grows, the contacts among particles tending to homogenize; (4) during initial gyratory compactions, the normal contact forces form a vertical distribution due to the aggregates’ gravity accumulation. The isotropic distribution of contact forces increases locally in the loading direction along the axis with a calibrated internal angle orientation (1.25°) in the earlier cyclic loading stage, then the local strong contacts decrease in the later stage, while the strength of the force chains in other directions increase. The anisotropy of aggregate contact force networks tends to weaken. In other words, kneading and shearing action during gyratory compaction have a positive impact on the homogenization and isotropy of asphalt mixture contact forces. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

17 pages, 4316 KiB  
Article
Macroscopic Behavior and Microscopic Structure Evolution of Marine Clay in One-Dimensional Compression Revealed by Discrete Element Simulation
by Lisha Luo, Zhifu Shen, Hongmei Gao, Zhihua Wang and Xin Zhou
Processes 2021, 9(12), 2259; https://doi.org/10.3390/pr9122259 - 14 Dec 2021
Cited by 2 | Viewed by 1977
Abstract
Marine clay has been attracting in-depth research on its mechanical behavior and internal structure evolution, which are crucial to marine infrastructure safety. In the formation process of marine clay, including the sedimentation and consolidation stages, the compression behavior and internal structure evolution are [...] Read more.
Marine clay has been attracting in-depth research on its mechanical behavior and internal structure evolution, which are crucial to marine infrastructure safety. In the formation process of marine clay, including the sedimentation and consolidation stages, the compression behavior and internal structure evolution are highly dependent on the pore water salinity. Discrete element method (DEM) simulation is a powerful tool to study the microscopic mechanics behind the complicated macroscopic mechanical behavior of marine clay. In this study, a DEM simulation scheme is systematically proposed to numerically study the macroscopic beahvior and microscopic structure evolution of marine clay in one-dimensional compression that mimics the marine clay formation process. First, the proposed calculation scheme for double layer repulsive interaction and van der Waals interaction is introduced. Then, the developed DEM simulation scheme is validated by satisfactorily reproducing the experimentally observed one-dimensional compression curves and internal structure transition from an edge-to-edge/edge-to-face flocculated structure to a face-to-face dispersed structure. Finally, evolutions of coordinate number and fabric anisotropy are quantitatively evaluated in the microscopic view. The noticeable effects of ion concentration on the internal structure evlotion and mechanical behavior of marine clay have been examined and discussed. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

13 pages, 3033 KiB  
Article
Experimental and Discrete Element Model Investigation of Limestone Aggregate Blending Process in Vertical Static and/or Conveyor Mixer for Application in the Concrete Mixture
by Lato L. Pezo, Milada Pezo, Anja Terzić, Aca P. Jovanović, Biljana Lončar, Dragan Govedarica and Predrag Kojić
Processes 2021, 9(11), 1991; https://doi.org/10.3390/pr9111991 - 8 Nov 2021
Cited by 2 | Viewed by 1572
Abstract
The numerical model of the granular flow within an aggregate mixture, conducted in the vertical static and/or the conveyor blender, was explored using the discrete element method (DEM) approach. The blending quality of limestone fine aggregate fractions binary mixture for application in self-compacting [...] Read more.
The numerical model of the granular flow within an aggregate mixture, conducted in the vertical static and/or the conveyor blender, was explored using the discrete element method (DEM) approach. The blending quality of limestone fine aggregate fractions binary mixture for application in self-compacting concrete was studied. The potential of augmenting the conveyor mixer working efficiency by joining its operation to a Komax-type vertical static mixer, to increase the blending conduct was investigated. In addition the impact of the feed height on the flow field in the cone-shaped conveyor mixer was examined using the DEM simulation. Applying the numerical approach enabled a deeper insight into the quality of blending actions, while the relative standard deviation criteria ranked the uniformity of the mixture. The primary objective of this investigation was to examine the behavior of mixture for two types of blenders and to estimate the combined blending action of these two mixers, to explore the potential to augment the homogeneity of the aggregate fractions binary mixture, i.e., mixing quality, reduce the blending time and to abbreviate the energy-consuming. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Graphical abstract

20 pages, 9252 KiB  
Article
Discharge Flow of Spherical Particles from a Cylindrical Bin: Experiment and DEM Simulations
by Rafał Kobyłka, Joanna Wiącek, Piotr Parafiniuk, Józef Horabik, Maciej Bańda, Mateusz Stasiak and Marek Molenda
Processes 2021, 9(11), 1860; https://doi.org/10.3390/pr9111860 - 20 Oct 2021
Cited by 5 | Viewed by 2036
Abstract
A series of the DEM simulations of the outflow of wooden spheres from a flat-bottomed container was reported, considering the maximum diameter to arrest the flow. Numerical simulations of the discharge process were performed, and the micro-mechanics of the discharged particles were described. [...] Read more.
A series of the DEM simulations of the outflow of wooden spheres from a flat-bottomed container was reported, considering the maximum diameter to arrest the flow. Numerical simulations of the discharge process were performed, and the micro-mechanics of the discharged particles were described. The effect of the sliding friction coefficient between particles, rolling friction coefficient, and modulus of elasticity of particles on the clogging process was investigated. The results of the simulations of the mass flow rate of spheres have shown a fairly close agreement with the experimental results. The real particles of wood were not perfectly spherical, their properties were anisotropic, and their frictional properties were non-homogenously distributed on the surface. Nevertheless, these deviations from ideal conditions did not produce a considerable discrepancy in the results. No direct relationship between the interparticle friction and the clogging was found; however, a relationship between the stability of the dome formed at flow arrest and the rolling friction was observed. An increase in Young’s modulus of particles by two orders of magnitude did not affect the clogging process, but a slightly higher probability of clogging was found for softer particles. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

22 pages, 15618 KiB  
Article
Chrono::GPU: An Open-Source Simulation Package for Granular Dynamics Using the Discrete Element Method
by Luning Fang, Ruochun Zhang, Colin Vanden Heuvel, Radu Serban and Dan Negrut
Processes 2021, 9(10), 1813; https://doi.org/10.3390/pr9101813 - 13 Oct 2021
Cited by 13 | Viewed by 4661
Abstract
We report on an open-source, publicly available C++ software module called Chrono::GPU, which uses the Discrete Element Method (DEM) to simulate large granular systems on Graphics Processing Unit (GPU) cards. The solver supports the integration of granular material with geometries defined by triangle [...] Read more.
We report on an open-source, publicly available C++ software module called Chrono::GPU, which uses the Discrete Element Method (DEM) to simulate large granular systems on Graphics Processing Unit (GPU) cards. The solver supports the integration of granular material with geometries defined by triangle meshes, as well as co-simulation with the multi-physics simulation engine Chrono. Chrono::GPU adopts a smooth contact formulation and implements various common contact force models, such as the Hertzian model for normal force and the Mindlin friction force model, which takes into account the history of tangential displacement, rolling frictional torques, and cohesion. We report on the code structure and highlight its use of mixed data types for reducing the memory footprint and increasing simulation speed. We discuss several validation tests (wave propagation, rotating drum, direct shear test, crater test) that compare the simulation results against experimental data or results reported in the literature. In another benchmark test, we demonstrate linear scaling with a problem size up to the GPU memory capacity; specifically, for systems with 130 million DEM elements. The simulation infrastructure is demonstrated in conjunction with simulations of the NASA Curiosity rover, which is currently active on Mars. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

20 pages, 5374 KiB  
Article
Calibration of DEM for Cohesive Particles in the SLS Powder Spreading Process
by Marco Lupo, Diego Barletta, Daniele Sofia and Massimo Poletto
Processes 2021, 9(10), 1715; https://doi.org/10.3390/pr9101715 - 24 Sep 2021
Cited by 6 | Viewed by 2146
Abstract
In this paper, a new DEM calibration procedure based on two different types of procedures to compare simulation with experiments is proposed. The aim is to find the values of the interfacial adhesive surface energy and the coefficient of rolling friction between the [...] Read more.
In this paper, a new DEM calibration procedure based on two different types of procedures to compare simulation with experiments is proposed. The aim is to find the values of the interfacial adhesive surface energy and the coefficient of rolling friction between the particles to be used in the simulation. The approach adopted is the so-called Bulk Calibration method. The experimental values of the angle of repose and unconfined yield strength, found with a static testing method and by shear testing, respectively, are compared, respectively, with the angle of repose, found in a simulation reproducing the experimental procedure, and the unconfined yield strength, obtained from an idealized uniaxial testing procedure. The simulated DEM particles are spheres equipped with the Hertz Mindlin with JKR contact model. The results suggest that a bulk calibration approach is not able to provide results that are consistent with two simple bulk property evaluations and, therefore, direct ways to estimate the surface energy based on the evaluation of interparticle forces, for example, should preferably be adopted. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

15 pages, 3270 KiB  
Article
Discrete Element Simulation Based on Elastic–Plastic Damping Model of Corn Kernel–Cob Bonding Force for Rotation Speed Optimization of Threshing Component
by Yajun Yu, Liangshan Li, Jiale Zhao and Xiaogeng Wang
Processes 2021, 9(8), 1410; https://doi.org/10.3390/pr9081410 - 16 Aug 2021
Cited by 6 | Viewed by 1952
Abstract
Current corn kernel-cob bonding mechanics models (LSD models) uniformly consider the bonding force changes during the maize threshing operation as an elastic change, resulting in computational errors of up to 10% or more in discrete element simulations. Due to the inability to perform [...] Read more.
Current corn kernel-cob bonding mechanics models (LSD models) uniformly consider the bonding force changes during the maize threshing operation as an elastic change, resulting in computational errors of up to 10% or more in discrete element simulations. Due to the inability to perform high-precision discrete element simulation of the mechanics characteristics during the corn threshing operation, the core operating parameters of the corn thresher (rotation speed of the threshing component) rely mainly on empirical settings, resulting in a consistent difficulty in exceeding 85% of the corn ear threshing rate. In this paper, by testing the mechanics characteristics of corn kernels, the bonding force is found to have both elastic and plastic changes during the threshing process. An elastic–plastic (EP) damping model of the corn kernel–cob bonding force was established by introducing a bonding restitution coefficient e to achieve an integrated consideration of the two changes. By testing the relationship between the properties of the corn ear itself and the model parameters, the pattern of the effect of the corn ear moisture content and the loading direction of the ear by force on the EP model parameters was found. By establishing a model of the relationship between the corn cob’s own properties and the model parameters, the EP model parameter values can be determined by simply determining the moisture content of the ear. In this paper, the EP model was established and the high-precision simulation and analysis of the process of bonding force variation between corn kernel and cob is realized on the self-developed AgriDEM software. At the meantime, the optimal values of the threshing component rotation speed under different conditions of moisture content of corn ear were obtained by establishing an optimization model of threshing component rotation speed. The test results showed that the corn ear threshing rate could reach more than 92.40% after adopting the optimized speed value of the threshing component in this paper. Meanwhile, the test results showed that the discrete element simulation results based on the EP model did not significantly differ from the measured results of the thresher. Compared with the most widely used LSD model, the EP model can reduce the computational error by 3.35% to 6.05%. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

13 pages, 2287 KiB  
Article
Evaluation of the Performance of a Combined Tillage Implement with Plough and Rotary Tiller by Experiment and DEM Simulation
by Jun Du, Yifan Heng, Kan Zheng, Wenliang Zhang, Jumin Zhang and Junfang Xia
Processes 2021, 9(7), 1174; https://doi.org/10.3390/pr9071174 - 6 Jul 2021
Cited by 8 | Viewed by 3002
Abstract
In order to improve the performance of tillage tool for straw incorporation in silty clay loam, a combined tillage implement with plough and rotary tiller was designed. Its performance on straw incorporation and power consumption was investigated, and the combined tillage types (CTSR [...] Read more.
In order to improve the performance of tillage tool for straw incorporation in silty clay loam, a combined tillage implement with plough and rotary tiller was designed. Its performance on straw incorporation and power consumption was investigated, and the combined tillage types (CTSR and CTDR) were compared with traditional tillage types including a sole plough type (SP and DP), a sole rotary tiller (RT), and a two-pass tillage type (SP+RT and DP+RT) in a rice field experiment. The effect of the forward speed and rotary speed for RT and CTSR were studied by DEM simulation. The ratio of straw coverage by CTSR and CTDR increased nearly 20% compared with RT, and the stability coefficient of tillage depth and CV of the surface evenness after tillage also improved in the field experiment. The total power of CTSR and CTDR was less than that of RT and two-pass tillage types by measurement. DEM simulation indicated that the total power of CTSR increased with the increase of the forward speed and rotary speed, and the reduction of the rotary power for the combined tillage implement can be obtained at a relatively high rotary speed. The combined tillage implement improved the performance on straw incorporation and had an advantage on power consumption at some operational conditions. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

16 pages, 3845 KiB  
Article
Optimal Design and Simulation Analysis of Spike Tooth Threshing Component Based on DEM
by Yajun Yu, Liangshan Li, Jiale Zhao, Xiangeng Wang and Jun Fu
Processes 2021, 9(7), 1163; https://doi.org/10.3390/pr9071163 - 4 Jul 2021
Cited by 10 | Viewed by 2641
Abstract
This paper takes a local drum-type corn thresher as an example. In order to make the threshing principle transform to the plate-tooth type, the width of the spike-tooth threshing component is increased gradually, and three threshing components of different shape and size are [...] Read more.
This paper takes a local drum-type corn thresher as an example. In order to make the threshing principle transform to the plate-tooth type, the width of the spike-tooth threshing component is increased gradually, and three threshing components of different shape and size are selected as the research objects. Based on the preliminary experimental research, the corn threshing process is simulation analyzed using the self-developed corn threshing process analysis software. The effects of the width of the threshing component on the corn ears threshing rate and kernel damage rate under different rates of drum rotation were studied from a macroscopic perspective. The results show that with the increase of drum rotation rate, both the corn ear threshing rate and kernel damage rate increase; with the increase of threshing component width, the threshing rate increases and the damage rate decreases; and when the component width is too large, the stacking between adjacent components has an impact on the threshing performance. The effects of threshing component width on the amount of kernel threshing and the total compressive force during the simulation time were investigated from microscopic perspective at different rates of drum rotation, and the results show that the microscopic analysis is consistent with the macroscopic analysis. Therefore, the optimization of the structural parameters and operating parameters of the threshing component was achieved. When the width of the threshing component was 25 mm and the roller speed was 187.50 rpm, the threshing performance was optimal, with a 98.04% corn ears threshing rate and a 2.56% kernel damage rate. This paper verifies the practical applicability of the corn threshing process analysis software and provides a reference for the optimal design of threshing devices. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

17 pages, 5547 KiB  
Article
DEM Parameter Calibration of Maize Seeds and the Effect of Rolling Friction
by Long Zhou, Jianqun Yu, Liusuo Liang, Yang Wang, Yajun Yu, Dongxu Yan, Kai Sun and Ping Liang
Processes 2021, 9(6), 914; https://doi.org/10.3390/pr9060914 - 22 May 2021
Cited by 17 | Viewed by 2453
Abstract
A set of suitable parameter values is crucial in discrete element method (DEM) simulations. As a non-spherical particle, the coefficients of rolling friction between maize seed particles and between the seed particles and the boundary are hard to measure directly and must be [...] Read more.
A set of suitable parameter values is crucial in discrete element method (DEM) simulations. As a non-spherical particle, the coefficients of rolling friction between maize seed particles and between the seed particles and the boundary are hard to measure directly and must be obtained by calibration. In this paper, taking three representative maize varieties as research objects, the necessity for the accurate calibration of the coefficients of rolling friction between seed particles and between seed particles and boundaries is investigated. Subsequently, by studying the sensitivity of the coefficients of rolling friction between seed particles and between seed particles and the boundary to the angle of repose test, the methods used to calibrate the coefficients of rolling friction between seed particles and between the particles and the boundary are determined. It can be seen from the results that the coefficients of rolling friction between the seed particles and between the seed particles and the boundary have a significant influence on the test results, so these two parameters must be accurately calibrated. Additionally, the coefficient of rolling friction between seed particles and the boundary has no effect on the piling angle, but the piling angle is highly sensitive to the coefficient of rolling friction between seed particles. By comparing the simulation results and the experimental results in the lifting cylinder and “self-flow screening” tests, the calibrated seed parameters were found to be accurate and valid. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Graphical abstract

16 pages, 3731 KiB  
Article
Analysis of Adhesion between Wet Clay Soil and Rotary Tillage Part in Paddy Field Based on Discrete Element Method
by Jian Cheng, Kan Zheng, Junfang Xia, Guoyang Liu, Liu Jiang and Dong Li
Processes 2021, 9(5), 845; https://doi.org/10.3390/pr9050845 - 12 May 2021
Cited by 13 | Viewed by 2946
Abstract
To analyze the process of wet clay soil adhering to the rotary tillage part during rotary tillage in paddy field, simulation tests were carried out based on the discrete element method (DEM) in this study. The Plackett-Burman (PB) test was applied to obtain [...] Read more.
To analyze the process of wet clay soil adhering to the rotary tillage part during rotary tillage in paddy field, simulation tests were carried out based on the discrete element method (DEM) in this study. The Plackett-Burman (PB) test was applied to obtain simulation parameters that significantly affected the soil adhesion mass. The Box-Behnken design (BBD) based on the principle of response surface method (RSM) was used to establish a regression model between significant parameters and soil adhesion mass. The soil adhesion mass obtained from the actual soil bin test as the response value was brought into the regression model. The optimal simulation parameters were obtained: the particle-particle coefficient of rolling friction, the particle-geometry coefficient of static friction, and the particle-particle JKR (Johnson-Kendall-Roberts) surface energy were 0.09, 0.81, and 61.55 J·m−2, respectively. The reliability of the parameters was verified by comparing the soil adhesion mass obtained under the optimal simulation parameters with the actual test value, and the relative error was 1.84%. Analysis of the rotary tillage showed that soil adhesion was mainly concentrated in the sidelong section of the rotary blade. The maximum number of upper soil particles adhering to the rotary tillage part was 2605 compared to the middle soil and lower soil layers. The longer the distance the rotary tillage part was operated in the soil for, the more soil particles would adhere to it. This study can provide a reference for the rational selection of simulation parameters for rotary tillage and the analysis of soil adhesion process in rotary tillage. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

19 pages, 10524 KiB  
Article
A Comparative Study on the Modelling of Soybean Particles Based on the Discrete Element Method
by Dongxu Yan, Jianqun Yu, Liusuo Liang, Yang Wang, Yajun Yu, Long Zhou, Kai Sun and Ping Liang
Processes 2021, 9(2), 286; https://doi.org/10.3390/pr9020286 - 2 Feb 2021
Cited by 8 | Viewed by 2327
Abstract
To solve the poor universality in the existing modelling approaches of soybean particles, we proposed a soybean particle modelling approach by combining five, nine, and 13 balls. The soybean seeds from three varieties (Suinong42, Jidou17, and Zhongdou39 with a sphericity of 94.78%, 86.86%, [...] Read more.
To solve the poor universality in the existing modelling approaches of soybean particles, we proposed a soybean particle modelling approach by combining five, nine, and 13 balls. The soybean seeds from three varieties (Suinong42, Jidou17, and Zhongdou39 with a sphericity of 94.78%, 86.86%, and 80.6%, respectively) are chosen as the study objects. By the comparisons between the simulation results and the test results in the “self-flow screening” and “piling angle” tests, it is concluded that the soybean particle modelling approach we presented in this paper is a universal modelling approach appropriate for soybean particles with different sphericities. The five-ball model is appropriate for the soybean particles with high sphericity, and the nine- or 13-ball models are applicable to those with low sphericity. The soybean particle modelling approach we presented is also compared with the ellipsoidal equation modelling approach for soybean particles and with the modelling approaches presented by other researchers. From an overall perspective, the soybean particle modelling approach we presented is better than the ellipsoidal equation modelling approach and those modelling approaches presented by other researchers. Additionally, it is shown that the multiple contacts issue in the multi-ball model has a little influence on the simulation results of soybean particle models. The study in this paper provides a new modelling approach for soybean particles in the DEM simulation of the contacts between soybean particles and the related machines. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

19 pages, 3705 KiB  
Article
A Discrete Element Method Study of Solids Stress in Cylindrical Columns Using MFiX
by Filippo Marchelli and Renzo Di Felice
Processes 2021, 9(1), 60; https://doi.org/10.3390/pr9010060 - 29 Dec 2020
Cited by 4 | Viewed by 1961
Abstract
Friction phenomena play a key role in discrete element method (DEM) modeling. To analyze this aspect, we employed the open-source program MFiX to perform DEM simulations of cylindrical vertical columns filled with solid particles. These are still associated with and described by the [...] Read more.
Friction phenomena play a key role in discrete element method (DEM) modeling. To analyze this aspect, we employed the open-source program MFiX to perform DEM simulations of cylindrical vertical columns filled with solid particles. These are still associated with and described by the pioneering model by the German engineer H.A. Janssen. By adapting the program’s code, we were able to gather numerous insights on the stress distribution within the solids. The column was filled with different amounts of solids and, after the system had stabilized, we assessed the pressure in the vertical and radial directions and the distribution of the friction force for all particles. An analysis of the bottom pressure for varying particle loads allowed us to infer that the program can correctly predict the expected asymptotical behavior. After a detailed assessment of the behavior of a single system, we performed a sensitivity analysis taking into account several of the variables employed in the simulations. The friction coefficient and filling rate seem to affect the final behavior the most. The program appears suitable to describe friction phenomena in such a static system. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

16 pages, 36093 KiB  
Article
Mixing of Particles in a Rotating Drum with Inclined Axis of Rotation
by Parag Widhate, Haiping Zhu, Qinghua Zeng and Kejun Dong
Processes 2020, 8(12), 1688; https://doi.org/10.3390/pr8121688 - 21 Dec 2020
Cited by 7 | Viewed by 5292
Abstract
Various experimental and numerical studies have been carried out to study the mixing processes inside rotating drums with a horizontal axis of rotation in the past, but little effort has been made to investigate the rotating drums with an inclined axis of rotation, [...] Read more.
Various experimental and numerical studies have been carried out to study the mixing processes inside rotating drums with a horizontal axis of rotation in the past, but little effort has been made to investigate the rotating drums with an inclined axis of rotation, though such inclined drums exist in industrial waste management, food processing, power and pharmaceutical industries. To fill this gap, in this work, the discrete element method was used to study the mixing phenomena of a rotating drum for different angles of inclination from 0° to 15°. It was found that for inclined rotating drums, the whole bed Lacey mixing index is higher than that for the horizontal drum by 7.2% when the angle of inclination is 10°. The mixing index is related to the area ratio of the active region to the whole bed and volumetric fill. Increase in volumetric fill would lead to the decrease of the mixing index. The mixing index and area ratio exhibit similar patterns along the length of the drum for different angles of inclination. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

16 pages, 10298 KiB  
Article
Coupled CFD-DEM Simulation of Seed Flow in an Air Seeder Distributor Tube
by Leno Guzman, Ying Chen and Hubert Landry
Processes 2020, 8(12), 1597; https://doi.org/10.3390/pr8121597 - 4 Dec 2020
Cited by 17 | Viewed by 3165
Abstract
Air seeding equipment consists of various machine components that rely on pneumatic conveying of seeds (granular material) for its operation. However, studying air seeder dynamic features in detail is difficult through experimental measurements. A simulation was performed to study seed motion in a [...] Read more.
Air seeding equipment consists of various machine components that rely on pneumatic conveying of seeds (granular material) for its operation. However, studying air seeder dynamic features in detail is difficult through experimental measurements. A simulation was performed to study seed motion in a horizontal tube section of an air seeder distributor system. The simulation incorporated two-way coupling between discrete element modeling (DEM) and computational fluid dynamics (CFD). Simulated particles were assigned material properties corresponding to field peas. Air velocity was assigned values of 10, 15, 20, and 25 m/s. The solid loading ratio (SLR) in this study included values between 0.5 and 3 to describe typical seed metering rates used in air seeding. The different pneumatic conveying conditions were studied to determine their overall effect on the average seed velocity and seed contact force. The simulation was validated through the comparison of average seed velocity data from the literature and current pneumatic conveying theory. The effect of SLR on the average seed velocity was found to be not significant for the simulated SLR values. The CFD-DEM simulation was able to capture seed collisions between seeds and the surrounding boundaries. The seed contact force increased with the air velocity, and the number of seed collisions increased with the SLR. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

22 pages, 4229 KiB  
Article
Numerical Characterization of Cohesive and Non-Cohesive ‘Sediments’ under Different Consolidation States Using 3D DEM Triaxial Experiments
by Hadar Elyashiv, Revital Bookman, Lennart Siemann, Uri ten Brink and Katrin Huhn
Processes 2020, 8(10), 1252; https://doi.org/10.3390/pr8101252 - 5 Oct 2020
Cited by 5 | Viewed by 2852
Abstract
The Discrete Element Method has been widely used to simulate geo-materials due to time and scale limitations met in the field and laboratories. While cohesionless geo-materials were the focus of many previous studies, the deformation of cohesive geo-materials in 3D remained poorly characterized. [...] Read more.
The Discrete Element Method has been widely used to simulate geo-materials due to time and scale limitations met in the field and laboratories. While cohesionless geo-materials were the focus of many previous studies, the deformation of cohesive geo-materials in 3D remained poorly characterized. Here, we aimed to generate a range of numerical ‘sediments’, assess their mechanical response to stress and compare their response with laboratory tests, focusing on differences between the micro- and macro-material properties. We simulated two endmembers—clay (cohesive) and sand (cohesionless). The materials were tested in a 3D triaxial numerical setup, under different simulated burial stresses and consolidation states. Variations in particle contact or individual bond strengths generate first order influence on the stress–strain response, i.e., a different deformation style of the numerical sand or clay. Increased burial depth generates a second order influence, elevating peak shear strength. Loose and dense consolidation states generate a third order influence of the endmember level. The results replicate a range of sediment compositions, empirical behaviors and conditions. We propose a procedure to characterize sediments numerically. The numerical ‘sediments’ can be applied to simulate processes in sediments exhibiting variations in strength due to post-seismic consolidation, bioturbation or variations in sedimentation rates. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

15 pages, 4394 KiB  
Article
Mixing of Bi-Dispersed Milli-Beads in a Rotary Drum. Mechanical Segregation Analyzed by Lab-Scale Experiments and DEM Simulation
by Aline Mesnier, Roman Peczalski, Guilhem Mollon and Séverine Vessot-Crastes
Processes 2020, 8(9), 1166; https://doi.org/10.3390/pr8091166 - 17 Sep 2020
Cited by 3 | Viewed by 2199
Abstract
Mechanical flow and segregation phenomena within a bed composed of milli-metric size spherical beads rotated in a horizontal drum were investigated. The beads population was bi-dispersed, with two kinds of binary (half by half) compositions: a bi-size bed with two different sizes and [...] Read more.
Mechanical flow and segregation phenomena within a bed composed of milli-metric size spherical beads rotated in a horizontal drum were investigated. The beads population was bi-dispersed, with two kinds of binary (half by half) compositions: a bi-size bed with two different sizes and a bi-density bed with two different densities. The distributions of the beads were observed optically on the front side of the bed by means of a lab-scale drum prototype. Different numbers and lengths of peripheral straight baffles were tested as well as different drum filling ratios. The photographical data were processed to obtain the front layer mechanical segregation index. This experimental index was compared to the simulated one, obtained by means of commercial discrete element software EDEM. The simulations were corroborated by the experiments provided that the friction coefficients of the discrete elements method (DEM) model were correctly adjusted. The global segregation index was also calculated from simulation data for all considered cases and its values were lower and less sensitive to baffles’ configurations than those for the front layer. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

19 pages, 29323 KiB  
Article
Calculating the Binary Tortuosity in DEM-Generated Granular Beds
by Wojciech Sobieski
Processes 2020, 8(9), 1105; https://doi.org/10.3390/pr8091105 - 4 Sep 2020
Cited by 3 | Viewed by 2859
Abstract
In this paper, a methodology of calculating the tortuosity in three-dimensional granular beds saved in a form of binary geometry with the application of the A-Star Algorithm and the Path Searching Algorithm is presented. The virtual beds serving as examples are prepared with [...] Read more.
In this paper, a methodology of calculating the tortuosity in three-dimensional granular beds saved in a form of binary geometry with the application of the A-Star Algorithm and the Path Searching Algorithm is presented. The virtual beds serving as examples are prepared with the use of the Discrete Element Method based on data of real, existing samples. The obtained results are compared with the results described in other papers (obtained by the use of the Lattice Boltzmann Method and the Path Tracking Method) as well as with the selected empirical formulas found in the literature. It was stated in the paper that the A-Star Algorithm gives values similar (but always slightly underestimated) to the values obtained via approaches based on the Lattice Boltzmann Method or the Path Tracking Method. In turn, the Path Searching Algorithm gives results in the same value range as popular empirical formulas and additionally it is approximately two times faster than the A-Star Algorithm. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Graphical abstract

Review

Jump to: Research

18 pages, 1548 KiB  
Review
A Review of the Application of Discrete Element Method in Agricultural Engineering: A Case Study of Soybean
by Dongxu Yan, Jianqun Yu, Yang Wang, Long Zhou, Kai Sun and Ye Tian
Processes 2022, 10(7), 1305; https://doi.org/10.3390/pr10071305 - 1 Jul 2022
Cited by 10 | Viewed by 1871
Abstract
The discrete element method has become a common method for analyzing the contact interaction between particulate materials and between particles and mechanical components. It has been widely used in agricultural engineering and other fields. Taking soybean as an example, soybean seed particles always [...] Read more.
The discrete element method has become a common method for analyzing the contact interaction between particulate materials and between particles and mechanical components. It has been widely used in agricultural engineering and other fields. Taking soybean as an example, soybean seed particles always have contact effects between particles and mechanical components in the process of planting, harvesting, threshing, separation, cleaning, and processing. The discrete element method can be used to obtain information on the contact forces between seed particles and mechanical parts, as well as the velocity and displacement of seed particle motion from a microscopic perspective. This paper summarizes the application of the discrete element method in soybean cultivation and production processes in recent years. This will help future researchers to conduct relevant test studies, develop and improve existing research methods. It can also serve as a guide and reference for the production and processing of other granular materials and the optimization of agricultural machinery components. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-25
Back to TopTop