Academic literature on the topic 'Discrete numerical modelling (DEM)'
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Journal articles on the topic "Discrete numerical modelling (DEM)":
1
Braile, Domenica, Colin Hare, and Chuan-Yu Wu. "DEM modelling of swelling of grains." EPJ Web of Conferences 249 (2021): 14011. http://dx.doi.org/10.1051/epjconf/202124914011.
Abstract:
Swelling of grains due to water absorption is ubiquitous in many natural materials and industrial products. Hence, a thorough understanding of grain swelling is of great scientific importance. An experimental investigation can only provide limited information, whereas great insight could be gained from numerical modelling, rigorous numerical models for describing particle swelling are essential. Thus, the objective of this study is to develop and validate a discrete element method (DEM) model for swelling of grains. A first order kinetic model was introduced to describe the swelling of a single grain, and subsequently implemented into the DEM code LIGGGHTS. Model validation was performed by comparing the time evolution of the expansion of a packed bed made of super absorbent polymer (SAP) particles obtained numerically and experimentally. It was demonstrated that the developed model can accurately predict the bed expansion. The validated model was then used to investigate the effect of material properties on the swelling behaviour using rice and SAP as the model materials. It is shown that the swelling depends significantly on material properties, as expected; the expansion of the powder bed made of rice is much lower than that of SAP. The developed model could be further advanced to study consequences of swelling phenomena in granular materials, such as segregation and heat generation.
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Jasevičius, Raimondas. "Numerical Modelling of Erythrocyte Sticking Mechanics." Applied Sciences 12, no. 24 (December 8, 2022): 12576. http://dx.doi.org/10.3390/app122412576.
Abstract:
The mechanics of thrombus formation includes the interaction of platelets, fibrin, and erythrocytes. The interaction was analyzed as the erythrocyte approaches the activated platelet and fibrin thrombus formation. The discrete element method (DEM) was used for the numerical experiment. Details of numerical experiments are presented by analyzing the dynamics of an erythrocyte in the process of interaction; a history of force, velocity, and displacement is given. It is usually assumed that the objects modeled by the DEM can oscillate during the sticking process. Modeling only this requires specialized knowledge and long-term research. However, by taking into account the influence of the fluid and modeling a soft biological cell, a completely different behavior can be achieved using the DEM method. The results of the numerical experiment show the different behavior of the erythrocyte when it interacts with a certain surface. Without taking into account the influence of the fluid in the sticking process, oscillations of the erythrocyte are observed. Meanwhile, after evaluating the influence of the liquid on the sticking process, there are no oscillations and unloading processes, which are typical for ultrafine objects. It is hoped that this will contribute to the study of the complex process of thrombus formation.
3
Guadagnin Moravia, Marcus, Pascal Villard, and Delma De Mattos Vidal. "Geogrid pull-out modelling using DEM." E3S Web of Conferences 92 (2019): 13015. http://dx.doi.org/10.1051/e3sconf/20199213015.
Abstract:
With the advancement of the use of synthetic reinforcements in geotechnics, a greater understanding of the mechanisms involved in soil-reinforcement interaction is the focus of major research centres on the subject. The topic of this study is the shearing behaviour at interfaces between granular materials and geogrids. The main objective is to provide a more fundamental understanding of some micromechanisms present in this type of interface, which in turn are important to optimize the design of such reinforcement. The numerical modelling of these reinforced structures must deal with the complexity of the material-reinforcement interaction problem; therefore, it requires specific numerical models whose formulations admit localized behaviours in the contacts as well as the granular nature of the material (e.g., soil, gravel, ballast). A robust and flexible way of modelling this problem is through the Discrete Element Method (DEM). The DEM proposes to model this granular nature by representing the soil as interacting constituent particles, whose behaviour is ruled by physical laws defined at the contact points. The numerical approach is desirable since it allows, in an articulated and relatively fast way, studying closely different regions of the interface, in order to identify factors and variables that are important for the problem. The purpose involves the DEM for a 3D modelling of a geogrid pull-out test to calculate the magnitude of forces in different elements of the geogrid (i.e., nodes, longitudinal and transverse members). Preparation of numerical samples has a particular importance in the final results of simulations. Thus, the numerical techniques used to obtain better geometry for the geogrid and a granular assembly with a representative grain rolling effect are also presented in this paper.
4
Jasevičius, R., and R. Kačianauskas. "Modelling deformable boundary by spherical particle for normal contact." Mechanics 68, no. 6 (April 4, 2024): 5–13. http://dx.doi.org/10.5755/j02.mech.36219.
Abstract:
The normal contact of the elastic spherical particle with deformable boundary is investigated in terms of the Discrete Element Method (DEM). The particle of the prescribed radius is moving under gravity and the initial velocity. The deformable boundary is treated as rigidly fixed spherical particle with variable elasticity modulus and variable radius. The limit case, approaching the infinite radius presents an elastic half-space, while increasing of the elasticity modulus presents the rigid boundary, respectively.
The linear model and the nonlinear Hertz contact model used in the discrete element method are investigated numerically by applying the 5th-order Gear’s predictorcorrector integration scheme. The numerical model is tested by comparing it with analytical solution. The time variations of the particle positions, velocities and accelerations are presented. On the basis of simulation results the limit values of the boundary particle parameters are evaluated and recommendations for the boundary article parameters required in DEM simulation are drown.
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Liu, Wenwei, and Chuan-Yu Wu. "Modelling Complex Particle–Fluid Flow with a Discrete Element Method Coupled with Lattice Boltzmann Methods (DEM-LBM)." ChemEngineering 4, no. 4 (October 7, 2020): 55. http://dx.doi.org/10.3390/chemengineering4040055.
Abstract:
Particle–fluid flows are ubiquitous in nature and industry. Understanding the dynamic behaviour of these complex flows becomes a rapidly developing interdisciplinary research focus. In this work, a numerical modelling approach for complex particle–fluid flows using the discrete element method coupled with the lattice Boltzmann method (DEM-LBM) is presented. The discrete element method and the lattice Boltzmann method, as well as the coupling techniques, are discussed in detail. The DEM-LBM is thoroughly validated for typical benchmark cases: the single-phase Poiseuille flow, the gravitational settling and the drag force on a fixed particle. In order to demonstrate the potential and applicability of DEM-LBM, three case studies are performed, which include the inertial migration of dense particle suspensions, the agglomeration of adhesive particle flows in channel flow and the sedimentation of particles in cavity flow. It is shown that DEM-LBM is a robust numerical approach for analysing complex particle–fluid flows.
6
Gholaminejad, Ahmadreza, Ahmad Mahboubi, and Ali Noorzad. "Combined DEM-FDM modelling of encased stone column." E3S Web of Conferences 92 (2019): 16012. http://dx.doi.org/10.1051/e3sconf/20199216012.
Abstract:
Combination of the continuum-based numerical methods and the discrete element method (DEM) could be a powerful way of simulating complex problems. This approach benefits from the capabilities of both methods. The main feature of the discrete element method is that the soil grains are considered as individual particles without need to impose any behaviour law in modelling the medium. The limitation of this method is, however, its high computational demand. In continuum based methods, on the other hand, it is impossible to trace micro scale phenomena. According to these facts, combining continuum and discrete methods is an optimal way in approaching geotechnical problems which deal with granular soils. In this approach, the coarse grain zone (medium) is modelled using DEM and the surrounding media are modelled using the continuum methods. Stone columns that are widely used for improving and/or increasing the strength of weak soils could be modelled using this type of coupled simulation. The Coarse aggregates present in the stone column make it appropriate for the coupled modelling. In this paper, the ordinary and encased stone columns have been simulated by combining 2D DEM and finite difference method (FDM). Clump technique was employed to achieve the interlocking of aggregate particles in DEM, and the surrounding cohesive soil was modelled using FDM. The obtained results were validated by the reported experimental results in the literature, indicating that the coupled DEM-FDM method is a robust way to simulate stone columns.
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Tan, Xin, Zhengbo Hu, Wengui Li, Suhua Zhou, and Tenglong Li. "Micromechanical Numerical Modelling on Compressive Failure of Recycled Concrete using Discrete Element Method (DEM)." Materials 13, no. 19 (September 29, 2020): 4329. http://dx.doi.org/10.3390/ma13194329.
Abstract:
This paper investigates the failure processes of recycled aggregate concrete by a model test and numerical simulations. A micromechanical numerical modeling approach to simulate the progressive cracking behavior of the modeled recycled aggregate concrete, considering its actual meso-structures, is established based on the discrete element method (DEM). The determination procedure of contact microparameters is analyzed, and a series of microscopic contact parameters for different components of modeled recycled aggregate concrete (MRAC) is calibrated using nanoindentation test results. The complete stress–strain curves, cracking process, and failure pattern of the numerical model are verified by the experimental results, proving their accuracy and validation. The initiation, growth, interaction, coalescence of microcracks, and subsequent macroscopic failure of the MRAC specimen are captured through DEM numerical simulations and compared with digital image correlation (DIC) results. The typical cracking modes controlled by meso-structures of MRAC are concluded according to numerical observations. A parameter study indicates the dominant influence of the macroscopic mechanical behaviors from the shear strength of the interfacial transition zones (ITZs).
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Huang, Xiao, Siyuan Li, Jionghao Jin, and Chong Shi. "Determining Digital Representation and Representative Elementary Volume Size of Broken Rock Mass Using the Discrete Fracture Network–Discrete Element Method Coupling Technique." Applied Sciences 14, no. 2 (January 10, 2024): 606. http://dx.doi.org/10.3390/app14020606.
Abstract:
Obtaining the digital characterization and representative elementary volume (REV) of broken rock masses is an important foundation for simulating their mechanical properties and behavior. In this study, utilizing the broken surrounding rock of the main powerhouse at the Liyang pumped storage power station as an engineering background, a three-dimensional fracture network generation program is first developed based on the theories of discrete fracture network (DFN) and discrete element method (DEM). The program is then integrated with a distinct element modelling platform to generate equivalent rock mass models for broken rock masses based on the DFN–DEM coupling technique. Numerical compression tests are conducted on cylindrical rock specimens produced using the proposed modelling approach, aiming to determining the REV size of the target rock masses at the Liyang power station. A comparative validation is also performed to examine the REV result obtained from the proposed approach, which adopted a REV measuring scale index (RMSI) to determine the REV size. Results indicate that the organic integration of DFN simulation techniques and DEM platforms can effectively construct numerical models for actual broken rock masses, with structural surface distributions statistically similar to the real ones. The results also show that the REV size of the investigated rock masses determined by the cylindrical rock models is 5 m × 10 m, which aligns with the size determined by the cubic rock models, as the target cubes show the same height as the cylindrical specimens. This study provides a model and parameter basis for the numerical calculation of the mechanical behavior of broken rock mass.
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Liu, Cong, Kang Wang, and Shen Zhou. "Non-spherical Particle Modelling Approach in Discrete Element Method and its Validations." Journal of Physics: Conference Series 2620, no. 1 (October 1, 2023): 012004. http://dx.doi.org/10.1088/1742-6596/2620/1/012004.
Abstract:
Abstract The discrete element method (DEM) is widely used for investigating the mechanical behaviours of complex physical system consisting of particles. In nature, the physical system such as rock and soil system, sand or flour are all composed of particles with different shapes. The particle shape can considerably influence nature characteristics in DEM simulation. Developing an effective particle shapes representation approach is a valuable task to improve the DEM modelling techniques. In this study, a super-quadrics function is introduced to represent the non-spherical particle shape. Furthermore, the corresponding contact detection and calculation algorithm named “deepest point method” is also explained to describe the complex contact relationships and calculate the contact forces between two irregular particles. At last, sandpile collapse simulations were conducted to validate the accuracy of the proposed approach. The numerical results indicate that the non-spherical particle modelling approach in this study can easily simulate most nature shape of particle system.
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Knak, Magdalena, Michał Nitka, Erwin Wojtczak, and Magdalena Rucka. "Modelling of Longitudinal Elastic Wave Propagation in a Steel Rod Using the Discrete Element Method." Materials 15, no. 8 (April 8, 2022): 2738. http://dx.doi.org/10.3390/ma15082738.
Abstract:
The paper deals with the issue of modelling elastic wave propagation using the discrete element method (DEM). The case of a longitudinal wave in a rod with a circular cross-section was considered. A novel, complex algorithm consisting of the preparation of models and simulation of elastic waves was developed. A series of DEM models were prepared for simulations, differing in discretisation and material parameters. Additional calculations with the finite element method (FEM) were performed. Numerical wave signals were obtained from each simulation and compared with experimental results to choose the best DEM model based on the correlation between the waveforms. Moreover, dispersion curves were prepared for each model to verify the agreement with the Pochhammer-Chree wave propagation theory. Both experimental and theoretical approaches indicated the same model as the most suitable. The analysis results allowed stating that DEM can be successfully used for modelling wave propagation in structural rods.
Dissertations / Theses on the topic "Discrete numerical modelling (DEM)":
1
Ochoa, Roman Jacqueline Vanessa. "Shaking table tests and DEM numerical modelling of a 3D-printed groin vault." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Abstract:
Preserving monumental historic buildings has not been an easy task due to their high vulnerability to seismic events. Throughout the years, several studies have tried to predict their behavior with the use of different numerical models, but the response is such complex that it remains a challenge. One of the trending tools to simulate masonry is the Discrete Element Model (DEM), but unfortunately few researches have implemented the physical simulation to validate the numerical results, and that is the main motivation of this study, which aims to contribute to the better understanding of masonry structures using a DEM and a physical model of large dimensions. This investigation is part of the “SEBESMOVA3D” project (SEeismic BEhavior of Scaled MOdels of groin VAults made by 3D printers) granted by the Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe SERA. This investigation starts from the design of a 2m x 2m groin vault, which represents a very common typology of ceiling systems in historical masonry monuments. During the first project campaign, the springings are fixed to the base. Each block is formed by a plastic skin (hollow section) and the inner core is filled with mortar to acquire the corresponding mass for dynamic tests. The blocks are easy and fast to assemble, so a significant number of tests can be executed. Prior to the experimental phase, a series of numerical simulations are carried out to predict both static and dynamic behavior based on a defined material characterization, allowing to establish a frequency range to test the physical model. Experimental tests are performed on a 3m x 3m shaking table, and the data obtained from a motion capture system is processed to evaluate displacements and cumulative damage. DEM simulations are run to calibrate and validate the numerical model. The results will be relevant and considered for the next project campaign.
2
Sundström, Anton. "Numerical modelling for characterization of the granular flows impact on the gas flow in a packed-bed-reactor." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79538.
Abstract:
The goal of the project was to characterize the granular flows impact on the gas flow in a packed-bed-reactor. The study was created at Swerim as a master's thesis for Luleå University of Technology. The packed-bed-reactor geometry used in this study is a scaled down blast furnace model. The granular flow was modelled using the discrete element method (DEM) in LS-DYNA. Four models were created with different sizes and size distribution of the particles. To study the granular flows impact on gas flow, porosity is extracted from the DEM models and analyzed, since porosity has a direct impact on the gas flow. The supervisors form Swerim, Joakim Eck and Martin Flemström created computational fluid dynamics (CFD) models in Ansys Fluent using the porosity from the DEM models. The DEM results are presented as granular flow profiles. This flow profile is created by injecting particles with alternating colors to see this profile. A total of 6 images are taken over the whole process. The porosity results are presented as a porosity field plots of the extracted porosity data using MATLAB. The CFD results are presented as plots of gas velocity and absolute pressure. The results show the different characteristics of the flow in the different DEM models, and how it relates to the different porosity fields that were found. Furthermore, the CFD models show how the flow of the gas is dependent on the porosity.
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Polwaththe, Gallage Hasitha Nayanajith. "Numerical modelling of deformation behaviour of red blood cells in microvessels using the coupled SPH-DEM method." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/91719/1/Hasitha%20Nayanajith_Polwaththe%20Gallage_Thesis.pdf.
Abstract:
This thesis developed an advanced computational model to investigate the motion and deformation properties of red blood cells in capillaries. The novel model is based on the meshfree particle methods and is capable of modelling the large deformation of red blood cells moving through blood vessels. The developed model was employed to simulate the deformation behaviour of healthy and malaria infected red blood cells as well as the motion of red blood cells in stenosed capillaries.
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Al, Tfaily Bilal. "Capacité prévisionnelle de la modélisation discrète pour application aux ouvrages géotechniques complexes." Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALI077.
Abstract:
L'ingénierie géotechnique est un domaine crucial dans la conception et la construction de fondations, de tunnels, de remblais et autres ouvrages en interaction avec le sol ou la roche. Cependant, la description de la réponse élastoplastique du sol, avec des déformations fortement non linéaires et irréversibles ainsi qu’une règle d'écoulement non associée, reste complexe. La difficulté est encore plus élevée dans le cas de chemins de chargement non monotones où les relations constitutives phénoménologiques nécessitent des paramètres d’histoire ad hoc et des essais mécaniques avancés pour leur calibration.La méthode des éléments discrets s'est avérée être une méthode efficace pour décrire quantitativement la réponse constitutive des sols, même dans le cas de chargements complexes (avec rotation des axes principaux de contraintes ou des cycles de chargement/déchargement) où les relations constitutives élastoplastiques conventionnelles peuvent conduire à des réponses simulées non réalistes. Pour les sols granulaires à granulométrie étroite, une représentation directe des grains du sol par des particules polyédriques ou à partir de level set est possible, tandis que pour les sols plus fins ou à granulométrie plus étalée, des solutions alternatives doivent être envisagées. Des particules sphériques avec des lois de contact enrichies ou des agrégats de sphères peuvent être utilisées pour conserver un modèle numérique relativement léger afin de résoudre des problèmes aux limites avec un coût en calcul limité. Cependant, même si ces modèles donnent des résultats satisfaisants pour des essais de cisaillement direct ou des compressions triaxiales drainées par rapport aux mesures expérimentales, leur validation par rapport à des trajets de chargement plus complexes tels que la compression isochore ou le chemin à déviateur de contrainte constant présente encore des difficultés, en particulier pour les assemblages granulaires initialement lâches.Dans cette étude, nous proposons tout d'abord de comparer de tels modèles. Cette comparaison se fait en termes de capacités prédictives à l'échelle macroscopique des réponses constitutives des sols, en particulier pour des trajets de chargement complexes. Deux types de modèles discrets sont considérés : (i) des particules sphériques avec une résistance au roulement, (ii) des agrégats simples composés de 2 à 6 sphères. Les modèles sont calibrés à partir de deux compressions triaxiales drainées sur du sable d’Hostun dense et lâche. Ils sont ensuite évalués, en fonction de la réponse macroscopique, sur des trajets de chargement nettement différents des trajets de calibration (compressions isochores, chemins de contrainte circulaires dans le plan déviatoire, chemin à déviateur de contrainte constant, etc.).Ensuite, nous étudions l'importance de la description de l'anisotropie de la micro-structure initiale et de la loi de frottement inter-particules dans les réponses simulées des assemblages granulaires lâches pour différents types de chemins de chargement. Cela montre comment la combinaison des deux peut modifier de manière importante les réponses simulées pour certains chemins de chargement. Cette étude est réalisée avec un modèle numérique discret composé de sphères comparé à des résultats expérimentaux réalisés sur un sable.Enfin, le modèle est utilisé pour simuler l'interaction non linéaire entre une fondation superficielle d'une structure de bâtiment et le sol lors de sollicitations sismiques intenses, comme testé expérimentalement pour le projet TRISEE avec un modèle physique à échelle 1. Une technique de discrétisation adaptative est mise en œuvre pour limiter le nombre de particules dans un tel problème aux limites et rendre le calcul possible avec un ordinateur de bureau classique. Les résultats numériques sont comparés aux mesures expérimentales du projet TRISEE, ainsi qu'à des simulations numériques par éléments finis (FEM) ou des modèles basés sur des macro-élémentsGeotechnical engineering is a crucial field in the design and construction of foundations, embankments, tunnels, and other structures interacting with soil and rock. However, the description of the elastoplastic response of soil, with preponderant non-linear and non-reversible deformations together with a non-associative flow rule, is complex. The difficulty is even higher in the case of non-monotonous loading paths where phenomenological constitutive relations require ad-hoc history parameters and advanced experimental tests for their calibration.Discrete element method has been proved to be an effective method in predicting quantitatively the constitutive response of soils, even in the case of complex loadings (with rotation of principal stress directions, or loading/unloading cycles) where conventional elastoplastic constitutive relations may fail to simulate realistic responses. For granular soils with a narrow grading, a direct representation of soil grains by polyhedral particles or with the level set method is possible, whereas for finer soils, or soils with a wider grading, alternative solutions should be considered. Spherical particles with enriched contact laws (e.g. by introducing rolling resistance at the contact) or rather simplified clumps of spheres can be used to keep the model relatively light to tackle further boundary value problems with limited computational cost. However, even if the models provide satisfying results for direct shear tests or drained triaxial compression loading paths compared to experimental measurements, their validation with respect to more complex loading paths as the isochoric compression or the path at constant stress deviator still present difficulties, in particular for initially loose granular assemblies.First, this study aims to compare such different approaches in terms of the prediction abilities at the macroscopic scale of the constitutive responses of soils, particularly for complex loading paths. Two kinds of discrete models are considered: (i) spherical particles with rolling resistance, (ii) simple clumps made of 2 to 6 spheres. The models are calibrated from two drained triaxial compressions on dense and loose Hostun sand. They are then assessed, according to the macroscopic response, on loading paths significantly different from the calibration loading paths (isochoric compressions, circular stress paths in the deviatoric plane, constant deviatoric stress path, etc.).Then, we investigate the importance of the description of the anisotropy of the initial fabric and of the inter-particle friction law in the simulated responses of loose granular assembly to different kinds of loading paths. It shows how the combination of both can modify importantly the simulated responses to some kinds of loading paths. This investigation is carried out for a numerical discrete model made of spheres by comparison with experimental results on sand.Finally, the model is used to simulate the nonlinear interaction between a shallow foundation of building structure and the supporting soil during strong seismic loadings, as tested experimentally for the TRISEE project with a full scale physical model. An adaptative discretization technique is implemented to limit the number of particles in such a boundary value problem and make the computation possible with a conventional desktop computer. Numerical results are benchmarked against experimental measurements from the TRISEE project, and FEM numerical simulations or macro-element models
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Kuruneru, Sahan Trushad Wickramasooriya. "A coupled finite-volume & discrete-element method to investigate particle-laden gas flows and particle deposition in metal foam heat exchangers." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/125485/1/Sahan_Kuruneru_Thesis.pdf.
Abstract:
This thesis focuses on the development and implementation of an advanced numerical model to investigate complex fluid flow behaviour through novel metal foam heat exchangers used in various industrial applications such as computer heat sinks and air-conditioners. The developed numerical model permits engineers to better optimize heat exchanger designs. Moreover, the project delves into heat exchanger fouling which is a multifaceted issue in the industry. In this regard, a non-toxic and cost-effective anti-fouling heat exchanger fouling is proposed.
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Javaid, Mehshan. "Numerical modelling of one-dimensional discrete source detonation." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95251.
Abstract:
Detonation is a branch of combustion that is initiated by an exothermic chemical reaction and it results in a supersonic shock wave called the Detonation Wave. Generally detonation occurs in homogeneous reacting gaseous, liquid or solid media. However sometimes, detonation is also observed in highly non-uniform medium which contains detonable sources (reacting gaseous, liquid or solid media) in a discrete pattern. This project focuses on the study of effect of discrete energy sources on the detonation wave velocity with the help of numerical modeling and simulations. The energy release as a result of detonation is continuous for a homogeneous gaseous mixture and generally results in a Chapman Jouguet (CJ) Detonation Velocity. However in the presence of discrete energy sources, the detonation velocity comes out to be higher than the CJ Detonation Velocity as observed theoretical by Higgins A. (Proc. 20th ICDERS, Montreal, 2005). This project aims to find numerical solutions for highly discrete detonation systems to verify the already existing theoretical results for discrete detonation systems. For the calculation of detonation wave velocities for medium with discrete sources, numerical analysis was carried out on an in-house one dimension Euler code. Modifications in the code were made to use it for continuous detonation purpose initially to verify the exact CJ detonation velocity through the code and then at a later stage, other modifications were made to the code to use it for discrete detonation phenomenon. Using the in-house numerical code for solving supersonic flow problems, the continuous detonation system was modeled and the results obtained were within 0.05% difference with respect to the exact CJ Detonation Velocity. After wards, discrete detonation system was modeled and numerical experiments were performed. It was observed that the detonation wave velocity increases with the increase in discreteness of energy source which is consistent with theLa détonation est une branche de la combustion qui est initiée par une réaction chimique exothermique duquel en résulte une onde de choc supersonique appelé «Detonation Wave". Généralement la détonation se produit dans une réaction homogène gazeuse, liquide ou solide. Mais parfois, la détonation est également observée en un milieu hautement non-uniforme qui contient des sources detonable (réaction gazeux, liquide ou solide ) dans un motif discret. Ce projet se concentre sur l'étude des effets des sources d'énergie discrets sur la vitesse de l'onde de détonation à l'aide de la modélisation numérique et des simulations. La libération d'énergie à la suite de la détonation est continue pour un mélange homogène de gaz et aboutit généralement à une vélocité de détonation appelé Chapman Jouguet (CJ). Toutefois, en présence de sources d'énergie distinctes, la vitesse de détonation sort d'être supérieure à la vitesse de détonation CJ observée théorique par A. Higgins (Proc. 20th ICDERS, Montréal, 2005). Ce projet vise à trouver des solutions numériques pour les systèmes de détonation très discrète afin de vérifier l'existance des résultats théoriques pour les systèmes de détonation discrets. Pour le calcul de vitesses des ondes de détonation pour les moyennes avec des sources discrètes, l'analyse numérique a été réalisée sur une maison d'une dimension de code Euler. Ces modifications du code ont été apportées à des fins de détonation continue . D'abord pour vérifier la vitesse de détonation CJ exacte dans lc code, puis à un stade ultérieur, d'autres modifications ont été apportées au code utiliser pour le phénomène de détonation discrets. Afin de pouvoir utiliser la maison en code numérique pour résoudre les problèmes d'écoulement supersoniques, le système continue de détonation a été modélisé et les résultats obtenus ont été de 0,05% de différence par rapport à la vitesse exacte d
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Ngoma, Jeff. "Etude numérique et expérimentale de la déstabilisation des milieux granulaires immergés par fluidisation." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4712/document.
Abstract:
Ce travail de thèse a pour objet l’étude numérique et expérimentale de la déstabilisation de milieux granulaires immergés par fluidisation. Cette instabilité hydromécanique est un mécanisme précurseur de l’érosion régressive, processus de dégradation au coeur de la problématique de l’érosion interne des ouvrages hydrauliques en terre. La compréhension de ces mécanismes d’érosion nécessite une description rigoureuse du couplage et de l’interaction entre le fluide et les particules de sol. A cette fin, un modèle 2D a été utilisé en couplant deux méthodes particulaires, la méthode des éléments discrets (DEM) pour modéliser le comportement mécanique de la phase solide et la méthode Lattice Boltzmann (LBM) pour la phase fluide. Des expériences servant de validation à cette simulation numérique 2D ont également été réalisées en s’appuyant sur une technique de visualisation interne d’un empilement granulaire combinant l’ajustement d’indice de réfraction des deux phases et la fluorescence induite par plan laserThe subject of this thesis is the numerical analysis and experimental investigation of the destabilization of submerged granular media caused by fluidization. This hydromechanical instability is one of the mechanisms that may trigger the regressive erosion, which is one of the main degradation phenomena driving the internal erosion of earthen hydraulic constructions. Such erosion mechanisms can only be understood through a rigorous description of the coupling and interaction between the eroding fluid and the soil particles. For this purpose, a 2D model has been used coupling two different numerical techniques, namely the discrete element method (DEM) for modelling the mechanical behaviour of the solid phase and the Lattice Boltzmann method (LBM) for the fluid phase. The experimental validation of this numerical 2D simulation has been carried out using two optical techniques for the internal visualization of a granular sample, namely the adjustment of the refraction index of the two phases and the laser-induced fluorescence
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Brown, Nicholas John. "Discrete element modelling of cementitious materials." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8011.
Abstract:
This thesis presents a new bonded particle model that accurately predicts the wideranging behaviour of cementitious materials. There is an increasing use of the Discrete Element Method (DEM) to study the behaviour of cementitious materials such as concrete and rock; the chief advantage of the DEM over continuum-based techniques is that it does not predetermine where cracking and fragmentation initiate and propagate, since the system is naturally discontinuous. The DEM’s ability to produce realistic representations of cementitious materials depends largely on the implementation of an inter-particle bonded-contact model. A new bonded-contact model is proposed, based on the Timoshenko beam theory which considers axial, shear and bending behaviour of inter-particle bonds. The developed model was implemented in the commercial EDEM code, in which a thorough verification procedure was conducted. A full parametric study then considered the uni-axial loading of a concrete cylinder; the influence of the input parameters on the bulk response was used to produce a calibrated model that has been shown to be capable of producing realistic predictions of a wide range of behaviour seen in cementitious materials. The model provides useful insights into the microscopic phenomena that result in the bulk loading responses observed for cementitious materials such as concrete. The new model was used to simulate the loading of a number of deformable structural elements including beams, frames, plates and rings; the numerical results produced by the model provided a close match to theoretical solutions.
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Durrani, Imran K. "Numerical modelling of discrete pile rows to stabilise slopes." Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438556.
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Wessling, Albin. "Towards Discrete Element Modelling of Rock Drilling." Licentiate thesis, Luleå tekniska universitet, Material- och solidmekanik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-83911.
Books on the topic "Discrete numerical modelling (DEM)":
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Portela, A. Finite elements using Maple: A symbolic programming approach. Berlin: Springer, 2002.
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Konietzky, Heinz, ed. Numerical Modelling of Discrete Materials in Geotechnical Engineering, Civil Engineering and Earth Sciences. CRC Press, 2004. http://dx.doi.org/10.1201/9780203023983.
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Konietzky, Heinz. Numerical Modelling of Discrete Materials in Geotechnical Engineering, Civil Engineering and Earth Sciences: Proceedings of the First International UDEC/3DEC Symposium, Bochum, Germany, 29 September - 1 October 2004. Taylor & Francis Group, 2004.
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Konietzky, Heinz. Numerical Modelling of Discrete Materials in Geotechnical Engineering, Civil Engineering and Earth Sciences: Proceedings of the First International UDEC/3DEC Symposium, Bochum, Germany, 29 September - 1 October 2004. Taylor & Francis Group, 2004.
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Konietzky, Heinz. Numerical Modelling of Discrete Materials in Geotechnical Engineering, Civil Engineering and Earth Sciences: Proceedings of the First International UDEC/3DEC Symposium, Bochum, Germany, 29 September - 1 October 2004. Taylor & Francis Group, 2004.
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Konietzky, Heinz. Numerical Modelling of Discrete Materials in Geotechnical Engineering, Civil Engineering and Earth Sciences: Proceedings of the First International UDEC/3DEC Symposium, Bochum, Germany, 29 September - 1 October 2004. Taylor & Francis Group, 2004.
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Konietzky, Heinz. Numerical Modelling of Discrete Materials in Geotechnical Engineering, Civil Engineering and Earth Sciences: Proceedings of the First International UDEC/3DEC Symposium, Bochum, Germany, 29 September - 1 October 2004. Taylor & Francis Group, 2014.
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Charafi, A., and Artur Portela. Finite Elements Using Maple: A Symbolic Programming Approach (Engineering Online Library). Springer, 2003.
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Charafi, A., and Artur Portela. Finite Elements Using Maple: A Symbolic Programming Approach. Springer, 2011.
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Eimanis, Mārcis. Usage of Double-Helical Propulsion Principle in Underwater Vehicles. RTU Press, 2022. http://dx.doi.org/10.7250/9789934227370.
Abstract:
The Thesis describes a new underwater vehicle propulsion type developed by the author. Flow and vehicle interaction dynamics are studied, and factors impacting the flow, control methods and the ability to move in other media (in addition to fluid) are reviewed. A geometry of the propulsion system was created by studying its hydrodynamic properties using special CFD software. A mathematical model for the control system was created. The dynamics of the underwater vehicle were modelled with the multibody dynamics modelling software MSC Adams, using the developed control system and the water resistance model developed with CFD software. Flow dynamics were combined with multibody mechanism dynamics using the metamodeling and numerical experiment approach. Numerical experiments in bulk or granular media were performed using the discrete element method, simulating the vehicle movement using the EDEM software. Within the framework of the Thesis, a prototype of the model was also created for observing the model behaviour in real-life conditions. High-quality and good fit results were obtained from the mathematical model and the physical prototype dynamics, proving the performance of both the new propulsion principle and the control system.
Book chapters on the topic "Discrete numerical modelling (DEM)":
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Yoshioka, Keita, Mathias Nest, Daniel Pötschke, Amir Shoarian Sattari, Patrick Schmidt, and David Krach. "Numerical Platform." In GeomInt–Mechanical Integrity of Host Rocks, 63–95. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-61909-1_3.
Abstract:
AbstractAn essential scientific goal of the GeomInt project is the analysis of potentials and limitations of different numerical approaches for the modelling of discontinuities in the rocks under consideration in order to improve the understanding of methods and their synergies with regard to theoretical and numerical fundamentals. As numerical methods, the “Lattice Element Method” (LEM), the non-continuous discontinuum methods “Discrete Element Method” (DEM), the “Smoothed Particle Hydrodynamics” (SPH), the “Forces on Fracture Surfaces” (FFS) as well as the continuum approaches “Phase-Field Method” (PFM), “Lower-Interface-Method” (LIE), “Non-Local Deformation” (NLD) and the “Hybrid-Dimensional Finite-Element-Method” (HDF) will be systematically investigated and appropriately extended based on experimental results (Fig. 3.1).
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Fox, William P., and Richard D. West. "Modelling with Discrete Dynamical Systems and Modelling Systems of Discrete Dynamical Systems." In Numerical Methods and Analysis with Mathematical Modelling, 35–83. Boca Raton: Chapman and Hall/CRC, 2024. http://dx.doi.org/10.1201/9781032703671-3.
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Korotov, Sergey, and Michal Křížek. "Discrete Maximum Principles in Finite Element Modelling." In Numerical Mathematics and Advanced Applications, 580–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-642-18775-9_55.
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Brookes, C. L., and S. Mehrkar-Asl. "Numerical modelling of masonry using discrete elements." In Seismic Design Practice into the Next Century, 131–37. London: Routledge, 2022. http://dx.doi.org/10.1201/9780203740026-18.
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Brookes, C. L., and S. Mehrkar-Asl. "Numerical modelling of masonry using discrete elements." In Seismic Design Practice into the Next Century, 131–37. London: Routledge, 2022. http://dx.doi.org/10.1201/9780203740026-18.
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Perdang, J. "Discrete Map Simulation of Stellar Oscillations." In The Numerical Modelling of Nonlinear Stellar Pulsations, 333–59. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0519-1_21.
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Diakite, Ibrahim, and Benito M. Chen-Charpentier. "Effects of a Discrete Time Delay on an HIV Pandemic." In Analysis, Modelling, Optimization, and Numerical Techniques, 57–73. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-12583-1_4.
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Indraratna, Buddhima, Cholachat Rujikiatkamjorn, and Wadud Salim. "Discrete element modelling (DEM) of ballast densification and breakage." In Advanced Rail Geotechnology – Ballasted Track, 291–317. 2nd ed. London: CRC Press, 2023. http://dx.doi.org/10.1201/9781003278979-11.
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Zhao, Tian-Xiong, and Xia Li. "Numerical Investigation on Sediment Bed Erosion Based on CFD-DEM." In Dam Breach Modelling and Risk Disposal, 274–79. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-46351-9_28.
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Zhou, Wan-Huan, and Zhen-Yu Yin. "Shear Banding in 2D Numerical Interface Tests." In Practice of Discrete Element Method in Soil-Structure Interface Modelling, 25–52. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-0047-1_2.
Conference papers on the topic "Discrete numerical modelling (DEM)":
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Liu, Lei, Eleanor Bailey, Rocky Taylor, and Tony King. "Numerical Modelling of Ice Rubble Interactions Using Discrete Element Method." In ASME 2021 40th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/omae2021-62818.
Abstract:
Abstract A three-dimensional, freeze-bonded, Discrete Element Method (DEM) numerical model has been developed to simulate various ice rubble/ridge interaction scenarios. The numerical model was validated against the physical tests conducted by C-CORE under the Pipeline Ice Risk Assessment and Mitigation (PIRAM) Joint Industry Project. Accurate representation of ice block geometries and sizes distributions was achieved using clumped particles, rather than the traditional DEM spheres. With the use of clumped ice blocks the numerical model was able to characterize the initial keel conditions (macro porosity and freeze bond contacts) and capture interlocking behavior between ice blocks. A DEM gravel seabed model was then introduced to the clumped ice block model to allow for better representation of soil response during the simulated experiments. The main features of these model developments are described in this paper, along with a comparison of simulated results and large scale physical test results. From this work it was concluded that: (1) clumped ice blocks give more representative ice block shapes for an ice keel than spherical ice blocks, which better capture ice block interactions and overall ridge keel properties and behavior; and (2) a DEM model of the seabed gravel provided a better representation of the seabed than was possible with a continuous stiffness plane, which had important implications for modelling the keel-seabed interactions. The development and inclusion of these two new model features were found to significantly improve the accuracy of the DEM model in reproducing physical test results, while still being sufficiently computationally efficient as to allow for simulation of interactions full-scale ice ridges.
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Mathe, N. L., M. Ferentinou, and K. Esmaeili. "Use of Stochastic DFN-DEM Modelling for Overall and Inter-Ramp Slope Stability Analysis." In 3rd International Discrete Fracture Network Engineering Conference. ARMA, 2022. http://dx.doi.org/10.56952/arma-dfne-22-0047.
Abstract:
Abstract Geometric Discrete Fracture Network (DFN) models are constructed in this research project, where limited and insufficient field structural data were exploited statistically in terms of observed parameter distribution at the mine-scale perspective. The construction of a DFN model employing a disaggregate technique was suggested by descriptive statistics of intensities (P10), orientation and length. The DFN model was validated by field data. The calibrated DFN model was then exported in a two-dimensional Distinct Element Model (DEM) to assess the stability of a critical pit wall where the multiple block failures were recorded at the bench and inter-ramp slope scale. The DFN-DEM approach adopted in this study could model the slope stability state using the shear strength reduction (SSR) method. According to the results of the simulations, the critical strength reduction factor (SRF) values derived from each numerical simulation were highly dependent on the DFN geometry configuration, and the trace length. To quantify the uncertainty associated with the assumptions established during the DFN-DEM modelling process, a series of models were simulated with different DFN configuration. At the inter-ramp slope scale, the simulations were predominantly unstable (SRF≤1.0) over 30 DFN realisations. The probability of failure (PoF) averaged 70% with a mean safety factor of 0.93 for the simulated DEM slope models while using the LE method, an average PoF of 40% and mean safety factor of 1.08 were estimated.
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Ciantia, Matteo. "Continuum (PFEM) and discrete (DEM) modelling of pile installation in rocks." In UK Association for Computational Mechanics Conference 2024. Durham University, 2024. http://dx.doi.org/10.62512/conf.ukacm2024.001.
Abstract:
Recent advancements in computational efficiency have enabled the application of advanced numerical models to solve challenging large-displacement soil structure interaction problems such as pile installation in non-linear irreversible materials prone to softening type of behaviour. Such challenging problems however require specialized approaches due to material and geometrical non linearities combined to the large deformation soil-structure interaction. This paper presents a comparison of two approaches for modelling open ended (OE) pile installation in soft, crushable and collapsible rocks. The first approach employs the Discrete Element Method (DEM), which represents the rock as separate particles bonded together, and introduces a new contact model for highly porous rocks. The second approach uses the Geotechnical Particle Finite Element Method (GPFEM) and investigates the coupled hydromechanical effects during pile installation using a robust and mesh-independent implementation of an elastic-plastic constitutive model at large strains. The DEM approach explores the micromechanical features of pile plugging and unveils the mechanisms behind radial stress distributions inside and outside the plug. The study highlights the strengths and limitations of each modelling technique, providing insights into the behaviour of OE piles installed in soft rocks
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Maramizonouz, Sadaf, and Sadegh Nadimi. "Accounting for Particle Morphology in CFD-DEM Modelling." In UK Association for Computational Mechanics Conference 2024. Durham University, 2024. http://dx.doi.org/10.62512/conf.ukacm2024.074.
Abstract:
In this study, the drag force acting on real irregular particles with various morphologies belonging to the four shape categories of the Zingg chart is estimated using the empirical models proposed in literature and the results are compared to the drag force obtained through computational fluid dynamics (CFD). Then, the chosen drag models are utilised to numerically simulate the flow of irregular particles through air along a cylindrical pipe, their exit at the nozzle, and their entrainment at a certain spot. The dynamics of the particulate material is simulated using discrete element method (DEM) modelling that is one-way coupled to CFD simulations via the drag force exerted on the particles. It is observed that particle morphology significantly influences the particle flow dynamics.
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Dai, Jie, and Heather Peng. "Discrete Element Modelling of Pack Ice Interaction With Floating Structures." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41916.
Abstract:
This paper presents a two-dimensional numerical model for ship-ice interaction simulatiion using the discrete element method (DEM). The simulation was conducted for a broken ice field with hundreds of circular ice floes and various combinations of ice conditions. A viscous-elastic ice rheology was adopted to model the dynamic behavior of each individual ice floe. Both ship-ice and ice-ice contacts were considered in the interaction force. Environment forces, including wind force and wave force, were calculated by empirical formulas. An algorithm was developed to log each contact and solve motions of individual ice floe and the ship. The resistance of ship advancing in ice was predicted and compared with model test results.
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Alihosseini, Maryam, and Paul Uwe Thamsen. "Experimental and Numerical Investigation of Sediment Transport in Sewers." In ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83274.
Abstract:
Sewer sediment deposition represents a crucial aspect of the maintenance of wastewater systems and has negative effects on the system itself as well as the environment. Therefore, it is important to design combined sewers, as sewage collection systems with high deposition risk, with adequate self-cleansing velocity to avoid the deposition. Despite the large number of investigations, the lack of knowledge about the particle behaviour in sewers remains a major problem in the field of sewer management. In the present work, the transport of sediments in partially filled channels is investigated experimentally and the results are compared to 3D-simulations performed with a coupled Computational Fluid Dynamics (CFD) model and Discrete Element Method (DEM). This research aims to investigate the self-cleansing design concept for uniform non-cohesive sediments based on moving of existing sediments on the sewer bed. The CFD part of the simulation is carried out in the commercial CFD software ANSYS Fluent, which is two-way coupled to the commercial DEM software EDEM through its User Defined Function. EDEM enhances the particle handling capability by resolving particle contacts, modelling bonded particles and non-spherical particles. The multiphase model Volume of Fluid (VOF) is used to capture the water and air interaction and the Discrete Phase Model (DPM) is applied to track the injected EDEM-particles. This paper also examines the applicability and limitations of this coupling method in simulation of sewer systems.
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Wrenger, Hendrik, Bruno Sainte-Rose, Christoph Goniva, and Renan Hilbert. "Plastic Accumulation in Front of a Plate in Cross Flow: Model Scale Test and CFD-DEM Modelling." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-96095.
Abstract:
Abstract Results of a flume experiment and numerical model of plastic accumulation in front of a plate are presented. The single phase CFD-DEM model formed a successful benchmark case to model plastic accumulation inside an ocean cleanup system. A fixed wooden plate was placed in a steady cross flow and plastic was released upstream of it. We recorded the evolution of the plastic accumulation profiles under slowly increasing plastic load. Experimental parameters were the flow velocity, draft of the plate (varying the plate Froude number) as well as three different types of plastic particles. The accumulation of oil in front of barriers and parallels to the phenomena of plastic accumulation were reviewed. As a second part of the project we used the open source CFD-DEM code CFDEM® to reproduce the flume experiment. It couples the discrete element method (DEM) software LIGGGHTS® and the open source computational fluid dynamics (CFD) software OpenFOAM®. A linear relationship of the relative depth of the accumulation with the Froude number of the plate was found for a given type of particle and reproduced in the numerical model. We identified limitations of the experimental setup, calibration experiments and the single phase CFD-DEM approach and outlined the steps for further research.
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Schiavoni, M. "Some recent advances and applications in Distinct Element modelling of masonry structures." In AIMETA 2022. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902431-51.
Abstract:
Abstract. In this paper, advanced numerical models are used to study the progressive damage of a historic building, namely the Palazzo of Podestà and the Civic Tower of Accumoli (central Italy). The dynamic behaviour of the structure is analyzed following important seismic events such as those that occurred in 2016-2017. Discontinuous and continuous approaches are used. In the formers, the masonry response is represented both with Discrete Element Method (DEM) and the Non-Smooth Contact Dynamic (NSCD) method; in the latter the masonry nonlinearity is replicated using the Concrete Damage Plasticity (CDP) model. The numerical results showed a good correspondence of all the approaches with the real damage suffered by the structure after the seismic sequence.
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Fredj, Abdelfettah, Aaron Dinovitzer, Amir Hassannejadasl, Richard Gailing, and Millan Sen. "Application of the Discrete Element Method (DEM) to Evaluate Pipeline Response to Slope Movement." In 2016 11th International Pipeline Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ipc2016-64508.
Abstract:
The long linear nature of buried pipelines results in the risk of interaction with a range of geotechnical hazards including active slopes and land surface subsidence areas. Ground movement induced by these geotechnical hazards can subject a pipeline to axial, lateral flexural, and vertical flexural loading. The techniques to predict pipeline displacements, loads, stresses or strains are not well described in design standards or codes of practice. The results of geotechnical site observation, successive in-line inspection or pipeline instrumentation are used to infer pipeline displacement or strain accumulation and these techniques are often augmented through the application of finite element analysis. The practice of using finite element analysis for pipe-soil interaction has developed in recent years and is proving to be a useful tool in evaluating the pipeline behavior in response to ground movement. This paper considers pipeline response to geotechnical hazard-induced loading scenarios related to slope movement transverse to the pipeline axis. The details of the three-dimensional LS-DYNA-based BMT pipe-soil interaction model employing a discrete element method (DEM) are presented in this paper. The validation of the numerical models through comparison with medium-scale physical pipe-soil interaction tests are described to demonstrate that the models are capable of accurately simulating real world events. The models are further calibrated for nominal soil types to replicate the pipe-soil load displacement properties outlined in ASCE guideline recommendations by developing responses that closely agree with these results from the physical trials and engineering judgement. The utility of advanced pipe-soil interaction modelling in supporting strain-based pipeline integrity management or design is demonstrated by presenting the results of geotechnical hazard numerical simulations. These simulations are used to describe the sensitivity of pipeline displacements and strains to the demands of these geotechnical events and develop relationships between the geotechnical event key parameters and pipeline response.
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Kumar, Sourav, Ritvik Babbar, Rohan Pattankar, Nithin Venkatarama, Srinivasa Yenugu, and Ravi Duggirala. "Numerical Modelling of Stone Lofting by a Treaded Tyre." In Symposium on International Automotive Technology. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2024. http://dx.doi.org/10.4271/2024-26-0270.
Abstract:
<div class="section abstract"><div class="htmlview paragraph">In passenger cars, exterior damage due to external objects is a common and repetitive problem for the costumer. A vehicle running over an unpaved or granular road undergoes such damages where the tyre picks up stones (<span class="xref">Figure 1</span>) [<span class="xref">1</span>] and ejects them towards the vehicle exterior surfaces. These stones cause mechanical damage to the vehicle: affecting aesthetics, accelerating corrosion, and reducing safety. This mechanical damage is more severe in case of electrical vehicles as batteries are placed at the underside of the vehicle. <span class="xref">Figure 2</span> [<span class="xref">2</span>] shows an example damaged caused by stone chipping. Induced erosion due to chipping cause corrosion propagation on the peeled surface, <span class="xref">Figure 2</span> shows an example of such corrosion. So far, physical testing and analytical mathematical methods are the most common ways to evaluate damages. However, there is a need of computationally inexpensive, repeatable, and accurate method, which can account for the complex system. This paper describes a validated Multiphysics numerical model for stone lofting, using a stand- alone all-weather tyre. The presented Multiphysics model couples Discrete Element Method (DEM), Finite Element Method (FEM), Multi-body Dynamics (MBD). Results of this work correlate well with experimental findings from Andreas Schönberger [<span class="xref">3</span>]. These experiments were performed in a controlled environment with a standalone treaded tyre and for three different velocities of 30kmph, 50kmph and 80kmph which accounts for tyre rotation. The results presented in this work show that method used is capable to capture relevant physics and predict stone lofting numerically. This method is anticipated as a starting point for the development of more sophisticated numeric models for stone chipping prediction.</div></div>
Reports on the topic "Discrete numerical modelling (DEM)":
1
Zheng, Jinhui, Matteo Ciantia, and Jonathan Knappett. On the efficiency of coupled discrete-continuum modelling analyses of cemented materials. University of Dundee, December 2021. http://dx.doi.org/10.20933/100001236.
Abstract:
Computational load of discrete element modelling (DEM) simulations is known to increase with the number of particles. To improve the computational efficiency hybrid methods using continuous elements in the far-field, have been developed to decrease the number of discrete particles required for the model. In the present work, the performance of using such coupling methods is investigated. In particular, the coupled wall method, known as the “wall-zone” method when coupling DEM and the continuum Finite Differences Method (FDM) using the Itasca commercial codes PFC and FLAC respectively, is here analysed. To determine the accuracy and the efficiency of such a coupling approach, 3-point bending tests of cemented materials are simulated numerically. To validate the coupling accuracy first the elastic response of the beam is considered. The advantage of employing such a coupling method is then investigated by loading the beam until failure. Finally, comparing the results between DEM, DEM-FDM coupled and FDM models, the advantages and disadvantages of each method are outlined.
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Wang, Wei, Michael Brown, Matteo Ciantia, and Yaseen Sharif. DEM simulation of cyclic tests on an offshore screw pile for floating wind. University of Dundee, December 2021. http://dx.doi.org/10.20933/100001231.
Abstract:
Screw piles need to be upscaled for offshore use e.g. being an alternative foundation and anchor form for offshore floating wind turbines, although the high demand of vertical installation forces could prevent its application if conventional pitch-matched installation is used. Recent studies, using numerical and centrifuge physical tests, indicated that the vertical installation force can be reduced by adopting over-flighting which also improved axial uplift capacity of the screw pile. The current study extends the scope to axial cyclic performance with respect to the installation approach. Using quasi-static discrete element method (DEM) simulation it was found that the over-flighted screw pile showed a lower displacement accumulation rate, compared to a pitch-matched installed pile, in terms of load-controlled cyclic tests. Sensitivity analysis of the setup of the cyclic loading servo shows the maximum velocity during the tests should be limited to avoid significant exaggeration of the pile displacement accumulation but this may lead to very high run durations.
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Tan, Peng, and Nicholas Sitar. Parallel Level-Set DEM (LS-DEM) Development and Application to the Study of Deformation and Flow of Granular Media. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, March 2023. http://dx.doi.org/10.55461/kmiz5819.
Abstract:
We present a systematic investigation of computational approaches to the modeling of granular materials. Granular materials are ubiquitous in everyday life and in a variety of engineering and industrial applications. Despite the apparent simplicity of the laws governing particle-scale interactions, predicting the continuum mechanical response of granular materials still poses extraordinary challenges. This is largely due to the complex history dependence resulting from continuous rearrangement of the microstructure of granular material, as well as the mechanical interlocking due to grain morphology and surface roughness. X-Ray Computed Tomography (XRCT) is used to characterize the grain morphology and the fabric of the granular media, naturally deposited sand in this study. The Level-Set based Discrete Element Method (LS-DEM) is then used to bridge the granular behavior gap between the micro and macro scale. The LS-DEM establishes a one-to-one correspondence between granular objects and numerical avatars and captures the details of grain morphology and surface roughness. However, the high-fidelity representation significantly increases the demands on computational resources. To this end a parallel version of LS-DEM is introduced to significantly decrease the computational demands. The code employs a binning algorithm, which reduces the search complexity of contact detection from O(n2) to O(n), and a domain decomposition strategy is used to elicit parallel computing in a memory- and communication-efficient manner. The parallel implementation shows good scalability and efficiency. High fidelity LS avatars obtained from XRCT images of naturally deposited sand are then used to replicate the results of triaxial tests using the new, parallel LS-DEM code. The result show that both micro- and macro-mechanical behavior of natural material is well captured and is consistent with experimental data, confirming experimental observation that the primary source of peak strength of sand is the mechanical interlocking between irregularly shaped grains. Specifically, triaxial test simulations with a flexible membrane produce a very good match to experimentally observed relationships between deviatoric stress and mobilized friction angle for naturally deposited sand. We then explore the viability of modeling dynamic problems with a new formulation of an impulse based LS-DEM. The new formulation is stable, fast, and energy conservative. However, it can be numerically stiff when the assembly has substantial mass differences between particles. We also demonstrate the feasibility of modeling deformable structures in the rigid body framework and propose several enhancements to improve the convergence of collision resolution, including a hybrid time integration scheme to separately handle at rest contacts and dynamic collisions. Finally, we extend the impulse-based LS-DEM to include arbitrarily shaped topographic surfaces and exploit its algorithmic advantages to demonstrate the feasibility of modeling realistic behavior of granular flows. The novel formulation significantly improves performance of dynamic simulations by allowing larger time steps, which is advantageous for observing the full development of physical phenomena such as rock avalanches, which we present as an illustrative example.
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A SIMPLE METHOD FOR A RELIABLE MODELLING OF THE NONLINEAR BEHAVIOUR OF BOLTED CONNECTIONS IN STEEL LATTICE TOWERS. The Hong Kong Institute of Steel Construction, March 2022. http://dx.doi.org/10.18057/ijasc.2022.18.1.6.
Abstract:
The behaviour of bolted connections in steel lattice transmission line towers affects their load-bearing capacity and failure mode. Bolted connections are commonly modelled as pinned or fixed joints, but their behaviour lies between these two extremes and evolves in a nonlinear manner. Accordingly, an accurate finite element modelling of the structural response of complete steel lattice towers requires the consideration of various nonlinear phenomena involved in bolted connexions, such as bolt slippage. In this study, a practical method is proposed for the modelling of the nonlinear response of steel lattice tower connections involving one or multiple bolts. First, the local load-deformation behaviour of single-bolt lap connections is evaluated analytically depending on various geometric and material parameters and construction details. Then, the predicted nonlinear behaviour for a given configuration serves as an input to a 2D/3D numerical model of the entire assembly of plates in which the bolted joints are represented as discrete elements. For comparison purposes, an extensive experimental study comprising forty-four tests were conducted on steel plates assembled with one or two bolts. This approach is also extended to simulate the behaviour of assemblies including four bolts and the obtained results are checked against experimental datasets from the literature. The obtained results show that the proposed method can predict accurately the response of a variety of multi-bolt connections. A potential application of the strategy developed in this paper could be in the numerical modelling of full-scale steel lattice towers, particularly for a reliable estimation of the displacements.