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1
Lee, Seungwoo, e Dongjoo Kim. "Particle Contact Model for CFD-DEM Simulations". Transactions of the Korean Society of Mechanical Engineers - B 43, n. 7 (31 luglio 2019): 479–87. http://dx.doi.org/10.3795/ksme-b.2019.43.7.479.
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Branco Jr, A. M. C., A. L. A. Mesquita e J. R. P. Vaz. "APPLICATION OF THE LINEAR SPRING-DASHPOT MODEL IN THE CFD-DEM SIMULATION OF ALUMINA FLUIDIZATION". Revista de Engenharia Térmica 14, n. 2 (31 dicembre 2015): 95. http://dx.doi.org/10.5380/reterm.v14i2.62141.
Testo completoAbstract (sommario):
The coupling of the Computational Fluid Dynamics (CFD) to the Discrete Element Method (DEM) to simulate fluidization is computationally demanding. Although the Linear Spring-Dahspot (LSD) model can help to reduce the CFD-DEM simulation runtime due to its simplicity, its applicability is not reasonable for all sorts of problems. The objective of the present work is to show the application of the LSD model to the CFD-DEM simulation of alumina fluidization. The simulations were carried out with the software ANSYS FLUENT 14.5 and divided into two parts: (1) the reproduction with ANSYS FLUENT of simulations from the literature in which the LSD model and a representative particle approach were used. (2) the simulation of alumina fluidization and validation with experimental data. The results of three main sets of parameters were analysed to include different DEM and CFD time steps, drag models, the representation of particles with both uniform size and particle size distribution, etc. The main conclusion of this work is that the LSD model and the CFD-DEM approach can be used to model the actual behaviour of alumina fluidized beds, but the high simulation runtime and the correct setting of the strategies used to control it are still limiting factors which deserve special attention.
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Ohsaki, Shuji, Ryosuke Mitani, Saki Fujiwara, Hideya Nakamura e Satoru Watano. "Numerical Simulation of Particle Motions in Cascade Impactor and Human Respiratory System". MATEC Web of Conferences 333 (2021): 02013. http://dx.doi.org/10.1051/matecconf/202133302013.
Testo completoAbstract (sommario):
Dry powder inhalations (DPIs) have gathered attention as a treatment for respiratory diseases due to the large effective absorption area in a human lung. A cascade impactor is generally used to investigate the inhalation performance of DPIs. For the improvement of the efficiency of DPIs, understanding the particle motion and deposition behavior in the human lung and the cascade impactor is required. In the present study, computer simulations were conducted to calculate the particle motion and deposition behavior in the human lung and the cascade impactor. As simulation methods, a coupling model of a computational fluid dynamics and a discrete phase method (CFD−DPM) and a coupling model of a CFD and a discrete element method (CFD−DEM) were used. The CFD−DEM simulation could reproduce the experimental particle deposition behavior in the cascade impactor, although it was difficult by the CFD−DPM simulation. Furthermore, the calculation results using the CFD−DEM simulation quantitatively demonstrated the higher particle reachability into the simple lung model when smaller particles were used. It was found that the CFD−DEM simulation is a powerful tool to calculate the particle motion and deposition behavior in the cascade impactor and human lung.
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Ohsaki, Shuji, Ryosuke Mitani, Saki Fujiwara, Hideya Nakamura e Satoru Watano. "Numerical Simulation of Particle Motions in Cascade Impactor and Human Respiratory System". MATEC Web of Conferences 333 (2021): 02013. http://dx.doi.org/10.1051/matecconf/202133302013.
Testo completoAbstract (sommario):
Dry powder inhalations (DPIs) have gathered attention as a treatment for respiratory diseases due to the large effective absorption area in a human lung. A cascade impactor is generally used to investigate the inhalation performance of DPIs. For the improvement of the efficiency of DPIs, understanding the particle motion and deposition behavior in the human lung and the cascade impactor is required. In the present study, computer simulations were conducted to calculate the particle motion and deposition behavior in the human lung and the cascade impactor. As simulation methods, a coupling model of a computational fluid dynamics and a discrete phase method (CFD−DPM) and a coupling model of a CFD and a discrete element method (CFD−DEM) were used. The CFD−DEM simulation could reproduce the experimental particle deposition behavior in the cascade impactor, although it was difficult by the CFD−DPM simulation. Furthermore, the calculation results using the CFD−DEM simulation quantitatively demonstrated the higher particle reachability into the simple lung model when smaller particles were used. It was found that the CFD−DEM simulation is a powerful tool to calculate the particle motion and deposition behavior in the cascade impactor and human lung.
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Derakhshani, Sayed M., Dingena L. Schott e Gabriel Lodewijks. "Calibrating the microscopic properties of quartz sand with coupled CFD-DEM framework". Engineering Computations 33, n. 4 (13 giugno 2016): 1141–60. http://dx.doi.org/10.1108/ec-04-2015-0105.
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Purpose – The macroscopic properties of dried sand can be correctly modelled when the accurate determination of the microscopic properties is available. The microscopic properties between the particles such as the coefficients of rolling (µ r) and sliding (µ s), are numerically determined in two different ways: with and without considering the fluid effect. In an earlier study, the microscopic properties were determined by discrete element method (DEM) and without considering the air effect on the macroscopic properties such as the Angle of Repose. The purpose of this paper is to recalibrate the microscopic properties through a coupling between the DEM and computational fluid dynamics (CFD). Design/methodology/approach – The first step is dedicated to the calibration of the CFD-DEM model through modelling a single particle sedimentation within air, water, and silicon oil. The voidage and drag models, the grid size ratio (D/dx), the domain size ratio (W/D), and the optimum coupling interval between the CFD and DEM were investigated through comparing the CFD-DEM results with the analytical solution and experimental data. The next step is about modelling an Hourglass with the calibrated CFD-DEM model to recalibrate the µ r and µ s of dried sand particles. Findings – It was concluded that the air has a minor effect on the macroscopic properties of the dried sand and the µ r and µ s that were obtained with the DEM can be utilized in the CFD-DEM simulation. Originality/value – Utilizing the granulometry of dried quartz sand in the calibration process of the CFD-DEM method has raised the possibility of using the µ r and µ s for other applications in future studies.
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Razavi, Fatemeh, Alexandra Komrakova e Carlos F. Lange. "CFD–DEM Simulation of Sand-Retention Mechanisms in Slurry Flow". Energies 14, n. 13 (24 giugno 2021): 3797. http://dx.doi.org/10.3390/en14133797.
Testo completoAbstract (sommario):
The primary motivation of this paper is to investigate the sand-retention mechanisms that occur at the opening of sand filters. Various retention mechanisms under various conditions are explored that have a particulate flow with a low concentration of sand particles (called slurry flow) such as particle shape, size, and concentration. The computational fluid dynamic (CFD)–discrete element method (DEM) model is applied to predict the retention mechanisms under steady flow conditions of the well-bore. By using coupled CFD–DEM (CFD to model the fluid flow, and DEM to model the particle flow), the physics involved in the retention mechanisms is studied. The coarse grid unresolved and the smoothed unresolved (refined grid unresolved) coupling approaches implemented in STAR-CCM+ (SIEMENS PLM) are used to transfer data between the fluid and solid phases and calculate the forces. The filter slots under investigation have different geometries: straight, keystone, wire-wrapped screen (WWS) and seamed slot and the particles are considered with different shapes and different aspect ratios and size distributions. The flow regime is laminar in all simulations conducted. The CFD–DEM model is validated from the perspectives of particle–fluid, particle–particle, and particle–wall interactions. Verification of the CFD–DEM model is conducted by mesh sensitivity analysis to investigate the coupling resolution between the CFD and DEM. By simulation of numerous slurry flow scenarios, three retention mechanisms including surface deposition, size exclusion, and sequential arching of particles are observed. However, the concentration of particles is too diluted to result in multiparticle arch formation. In the simulations, various conditions are tested to give us an insight into the parameters and conditions that could affect the occurrence of the retention mechanisms. As an example, the importance of the gravity force and interaction forces on retention mechanisms are confirmed at the microscale in comparison with others forces involved in retention mechanisms such as the drag force, lift force, cohesive force, buoyancy force, and virtual mass force.
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Liu, Daoyin, Zhonglin Zhang, Yaming Zhuang e Xiaoping Chen. "Comparison of CFD Simulation and Simplified Modeling of a Fluidized Bed CO2 Capture Reactor". International Journal of Chemical Reactor Engineering 14, n. 1 (1 febbraio 2016): 133–41. http://dx.doi.org/10.1515/ijcre-2015-0058.
Testo completoAbstract (sommario):
AbstractCO2 capture using solid sorbents in fluidized bed reactors is a promising technology. The multiphase CFD model is increasingly developed to study the reactors, but it is difficult to model all the realistic details and it requires significant computational time. In this study, both the multiphase CFD model (i.e., CFD-DEM model coupled with reaction) and the simplified reactor models (i.e., plug flow model and bubbling two-phase model) are developed for modeling a fluidized bed CO2 capture reactor. The comparisons are made at different gas velocities from fixed bed to fluidized bed. The DEM based model reveals a detailed view of CO2 adsorption process with particle flow dynamics, based on which the assumptions in the simplified models can be evaluated. The plug flow model predictions generally show similar trends to the DEM model but there are quantitative differences; thus, it can be used to determine the reactor performance limit. The bubbling two-phase model gives better predictions than the plug flow model because the effect of bubbles on the inter-phase mass transfer and reaction is included. In the future, a closer combination of the multiphase CFD simulation and the simplified reactor models will likely be an efficient design method of CO2 capture fluidized bed reactors.
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ZHOU, Z. Y., S. B. KUANG, K. W. CHU e A. B. YU. "Discrete particle simulation of particle–fluid flow: model formulations and their applicability". Journal of Fluid Mechanics 661 (25 agosto 2010): 482–510. http://dx.doi.org/10.1017/s002211201000306x.
Testo completoAbstract (sommario):
The approach of combining computational fluid dynamics (CFD) for continuum fluid and the discrete element method (DEM) for discrete particles has been increasingly used to study the fundamentals of coupled particle–fluid flows. Different CFD–DEM models have been used. However, the origin and the applicability of these models are not clearly understood. In this paper, the origin of different model formulations is discussed first. It shows that, in connection with the continuum approach, three sets of formulations exist in the CFD–DEM approach: an original format set I, and subsequent derivations of set II and set III, respectively, corresponding to the so-called model A and model B in the literature. A comparison and the applicability of the three models are assessed theoretically and then verified from the study of three representative particle–fluid flow systems: fluidization, pneumatic conveying and hydrocyclones. It is demonstrated that sets I and II are essentially the same, with small differences resulting from different mathematical or numerical treatments of a few terms in the original equation. Set III is however a simplified version of set I. The testing cases show that all the three models are applicable to gas fluidization and, to a large extent, pneumatic conveying. However, the application of set III is conditional, as demonstrated in the case of hydrocyclones. Strictly speaking, set III is only valid when fluid flow is steady and uniform. Set II and, in particular, set I, which is somehow forgotten in the literature, are recommended for the future CFD–DEM modelling of complex particle–fluid flow.
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Lvov, Vladislav, e Leonid Chitalov. "Semi-Autogenous Wet Grinding Modeling with CFD-DEM". Minerals 11, n. 5 (1 maggio 2021): 485. http://dx.doi.org/10.3390/min11050485.
Testo completoAbstract (sommario):
The paper highlights the features of constructing a model of a wet semi-autogenous grinding mill based on the discrete element method and computational fluid dynamics. The model was built using Rocky DEM (v. 4.4.2, ESSS, Brazil) and Ansys Fluent (v. 2020 R2, Ansys, Inc., United States) software. A list of assumptions and boundary conditions necessary for modeling the process of wet semi-autogenous grinding by the finite element method is presented. The created model makes it possible to determine the energy-coarseness ratios of the semi-autogenous grinding (SAG) process under given conditions. To create the model in Rocky DEM the following models were used: The Linear Spring Rolling Limit rolling model, the Hysteretic Linear Spring model of the normal interaction forces and the Linear Spring Coulomb Limit for tangential forces. When constructing multiphase in Ansys Fluent, the Euler model was used with the primary phase in the form of a pulp with a given viscosity and density, and secondary phases in the form of air, crushing bodies and ore particles. The resistance of the solid phase to air and water was described by the Schiller–Naumann model, and viscosity by the realizable k-epsilon model with a dispersed multiphase turbulence model. The results of the work methods for material interaction coefficients determination were developed. A method for calculating the efficiency of the semi-autogenous grinding process based on the results of numerical simulation by the discrete element method is proposed.
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Jaiswal, Atul, Minh Duc Bui e Peter Rutschmann. "Evaluation of RANS-DEM and LES-DEM Methods in OpenFOAM for Simulation of Particle-Laden Turbulent Flows". Fluids 7, n. 10 (21 ottobre 2022): 337. http://dx.doi.org/10.3390/fluids7100337.
Testo completoAbstract (sommario):
CFD-DEM modelling of particle-laden turbulent flow is challenging in terms of the required and obtained CFD resolution, heavy DEM computations, and the limitations of the method. Here, we assess the efficiency of a particle-tracking solver in OpenFOAM with RANS-DEM and LES-DEM approaches under the unresolved CFD-DEM framework. Furthermore, we investigate aspects of the unresolved CFD-DEM method with regard to the coupling regime, particle boundary condition and turbulence modelling. Applying one-way and two-way coupling to our RANS-DEM simulations demonstrates that it is sufficient to include one-way coupling when the particle concentration is small (O ~ 10−5). Moreover, our study suggests an approach to estimate the particle boundary condition for cases when data is unavailable. In contrast to what has been previously reported for the adopted case, our RANS-DEM results demonstrate that simple dispersion models considerably underpredict particle dispersion and previously observed reasonable particle dispersion were due to an error in the numerical setup rather than the used dispersion model claiming to include turbulence effects on particle trajectories. LES-DEM may restrict extreme mesh refinement, and, under such scenarios, dynamic LES turbulence models seem to overcome the poor performance of static LES turbulence models. Sub-grade scale effects cannot be neglected when using coarse mesh resolution in LES-DEM and must be recovered with efficient modelling approaches to predict accurate particle dispersion.
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Celik, Alptekin, Christian Bonten, Riccardo Togni, Christoph Kloss e Christoph Goniva. "A Novel Modeling Approach for Plastics Melting within a CFD-DEM Framework". Polymers 13, n. 2 (11 gennaio 2021): 227. http://dx.doi.org/10.3390/polym13020227.
Testo completoAbstract (sommario):
Existing three-dimensional modeling approaches to single-screw extrusion can be classified according to the process sections. The discrete element method (DEM) allows describing solids transport in the feed section. The melt flow in the melt section can be calculated by means of computational fluid dynamics (CFD). However, the current state of the art only allows a separate consideration of the respective sections. A joint examination of the process sections still remains challenging. In this study, a novel modeling approach is presented, allowing a joint consideration of solids and melt transport and, beyond that, the formation of melt. For this purpose, the phase transition from the solid to liquid states is modeled for the first time within the framework CFDEMCoupling®, combining CFD and DEM by a novel melting model implemented in this study. In addition, a melting apparatus for the validation of the novel melting model is set up and put into operation. CFD-DEM simulations are carried out in order to calculate the melting rate and are compared to experimental results. A good agreement between the simulation and experimental results is found. From the findings, it can be assumed that the CFD-DEM simulation of single-screw extruder with a joint consideration of the feed and melt section is feasible.
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Celik, Alptekin, Christian Bonten, Riccardo Togni, Christoph Kloss e Christoph Goniva. "A Novel Modeling Approach for Plastics Melting within a CFD-DEM Framework". Polymers 13, n. 2 (11 gennaio 2021): 227. http://dx.doi.org/10.3390/polym13020227.
Testo completoAbstract (sommario):
Existing three-dimensional modeling approaches to single-screw extrusion can be classified according to the process sections. The discrete element method (DEM) allows describing solids transport in the feed section. The melt flow in the melt section can be calculated by means of computational fluid dynamics (CFD). However, the current state of the art only allows a separate consideration of the respective sections. A joint examination of the process sections still remains challenging. In this study, a novel modeling approach is presented, allowing a joint consideration of solids and melt transport and, beyond that, the formation of melt. For this purpose, the phase transition from the solid to liquid states is modeled for the first time within the framework CFDEMCoupling®, combining CFD and DEM by a novel melting model implemented in this study. In addition, a melting apparatus for the validation of the novel melting model is set up and put into operation. CFD-DEM simulations are carried out in order to calculate the melting rate and are compared to experimental results. A good agreement between the simulation and experimental results is found. From the findings, it can be assumed that the CFD-DEM simulation of single-screw extruder with a joint consideration of the feed and melt section is feasible.
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Zhou, Haotong, Guihe Wang, Cangqin Jia e Cheng Li. "A Novel, Coupled CFD-DEM Model for the Flow Characteristics of Particles Inside a Pipe". Water 11, n. 11 (14 novembre 2019): 2381. http://dx.doi.org/10.3390/w11112381.
Testo completoAbstract (sommario):
This study developed a novel, 3D coupled computational fluid dynamics (CFD)-discrete element method (DEM) model by coupling two software programs, OpenFOAM and PFC3D, to solve problems related to fluid–particle interaction systems. The complete governing equations and the flow chart of the coupling calculations are clearly presented herein. The coupled CFD-DEM model was first benchmarked using two classic geo-mechanics problems, for which the analytical solutions are available. Then, the CFD-DEM model was employed to investigate the flow characteristics of a particle heap subjected to the effects of water inside a pipe under different conditions. The results showed that particle size and pipe inclination angle can significantly affect the particle flow morphology, total kinetic energy and erosion rate for mono-sized particles, whereas polydisperse particles had a slight effect. This model can accurately describe the flow characteristics of particles inside a pipe, and the results of this study were consistent with those of previous studies. The reliability of this model was further demonstrated, which showed that this model can provide valuable references for solving similar problems such as soil erosion and bridge scour problems.
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Puderbach, Vanessa, Kilian Schmidt e Sergiy Antonyuk. "A Coupled CFD-DEM Model for Resolved Simulation of Filter Cake Formation during Solid-Liquid Separation". Processes 9, n. 5 (9 maggio 2021): 826. http://dx.doi.org/10.3390/pr9050826.
Testo completoAbstract (sommario):
In cake filtration processes, where particles in a suspension are separated by forming a filter cake on the filter medium, the resistances of filter cake and filter medium cause a specific pressure drop which consequently defines the process energy effort. The micromechanics of the filter cake formation (interactions between particles, fluid, other particles and filter medium) must be considered to describe pore clogging, filter cake growth and consolidation correctly. A precise 3D modeling approach to describe these effects is the resolved coupling of the Computational Fluid Dynamics with the Discrete Element Method (CFD-DEM). This work focuses on the development and validation of a CFD-DEM model, which is capable to predict the filter cake formation during solid-liquid separation accurately. The model uses the Lattice-Boltzmann Method (LBM) to directly solve the flow equations in the CFD part of the coupling and the DEM for the calculation of particle interactions. The developed model enables the 4-way coupling to consider particle-fluid and particle-particle interactions. The results of this work are presented in two steps. First, the developed model is validated with an empirical model of the single particle settling velocity in the transition regime of the fluid-particle flow. The model is also enhanced with additional particles to determine the particle-particle influence. Second, the separation of silica glass particles from water in a pressurized housing at constant pressure is experimentally investigated. The measured filter cake, filter medium and interference resistances are in a good agreement with the results of the 3D simulations, demonstrating the applicability of the resolved CFD-DEM coupling for analyzing and optimizing cake filtration processes.
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Flamarz, Sherko. "Computational Study of Heat Transfer Behavior in Fluid-Solid Fluidized Beds." Sulaimani Journal for Engineering Sciences 7, n. 3 (30 dicembre 2020): 25–41. http://dx.doi.org/10.17656/sjes.10132.
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Heat transfer in fluid-solid fluidized beds is investigated using a combined of computational fluid dynamics (CFD) and discrete element method (DEM) approach, incorporated with a thermal model. The approach has taken into account almost all the mechanisms in heat transfer in fluidized beds. A comparison and validation of hydrodynamic and thermal data of fluidized bed obtained using CFD-DEM thermal approach with experimental and numerical results data in the literature is carried out. The simulations results reveal a good thermal steady state during the simulation time for calculating the thermal behaviors of fluidized beds like; the mean particle temperature, bed porosity, heat transfer coefficient and mean particle Reynolds number. The simulations results are showed a good agreement and consistency with the experimental and numerical data in the literatures. Thus, the integration of combined CFD-DEM with the thermal model is a step toward for the prediction, development the heat transfer efficiency in fluid-solid system, and the decrease of energy consumption of the industrial applications.
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Liu, Zihan, Huaqing Ma e Yongzhi Zhao. "CFD-DEM Simulation of Fluidization of Polyhedral Particles in a Fluidized Bed". Energies 14, n. 16 (12 agosto 2021): 4939. http://dx.doi.org/10.3390/en14164939.
Testo completoAbstract (sommario):
Fluidization of non-spherical particles is a common process in energy industries and chemical engineering. Understanding the fluidization of non-spherical particles is important to guide relevant processes. There already have been numerous studies which investigate the behaviors of different non-spherical particles during fluidization, but the investigations of the fluidization of polyhedral particles do not receive much attention. In this study, the investigation of the fluidization of polyhedral particles described by the polyhedron approach is conducted with a numerical CFD-DEM method. Experiments of the fluidization of three kinds of polyhedral particles are conducted under the same condition with corresponding simulations to validate the accuracy of our CFD-DEM model. The results indicate that our CFD-DEM model with the polyhedron approach can predict the behaviors of polyhedral particles with reasonable accuracy. Fluidization behaviors of different polyhedral particles are also investigated in this study. Compared to spherical particles, the motion of polyhedral particles is stronger, and mixing degree is higher under the same fluidization gas velocity.
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Yu, Yaxiong, Li Zhao, Yu Li e Qiang Zhou. "A Model to Improve Granular Temperature in CFD-DEM Simulations". Energies 13, n. 18 (11 settembre 2020): 4730. http://dx.doi.org/10.3390/en13184730.
Testo completoAbstract (sommario):
CFD-DEM (computational fluid dynamic-discrete element method) is a promising approach for simulating fluid–solid flows in fluidized beds. This approach generally under-predicts the granular temperature due to the use of drag models for the average drag force. This work develops a simple model to improve the granular temperature through increasing the drag force fluctuations on the particles. The increased drag force fluctuations are designed to match those obtained from PR-DNSs (particle-resolved direct numerical simulations). The impacts of the present model on the granular temperatures are demonstrated by posteriori tests. The posteriori tests of tri-periodic gas–solid flows show that simulations with the present model can obtain transient as well as steady-state granular temperature correctly. Moreover, the posteriori tests of fluidized beds indicated that the present model could significantly improve the granular temperature for the homogenous or slightly inhomogeneous systems, while it showed negligible improvement on the granular temperature for the significantly inhomogeneous systems.
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Mayank, K., M. Malahe, I. Govender e N. Mangadoddy. "Coupled DEM-CFD Model to Predict the Tumbling Mill Dynamics". Procedia IUTAM 15 (2015): 139–49. http://dx.doi.org/10.1016/j.piutam.2015.04.020.
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Gu, Yile, Ali Ozel e Sankaran Sundaresan. "A modified cohesion model for CFD–DEM simulations of fluidization". Powder Technology 296 (agosto 2016): 17–28. http://dx.doi.org/10.1016/j.powtec.2015.09.037.
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Liu, Daoyin, Berend G. M. van Wachem, Robert F. Mudde, Xiaoping Chen e J. Ruud van Ommen. "An adhesive CFD-DEM model for simulating nanoparticle agglomerate fluidization". AIChE Journal 62, n. 7 (27 marzo 2016): 2259–70. http://dx.doi.org/10.1002/aic.15219.
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Chen, Yong, Chuanliang Yan, Yuanfang Cheng, Zhongying Han e Yang Li. "Study on Agglomeration and Plugging Behavior of Fine Particles in Reservoir Based on DEM-CFD Coupling". Journal of Physics: Conference Series 2834, n. 1 (1 ottobre 2024): 012158. http://dx.doi.org/10.1088/1742-6596/2834/1/012158.
Testo completoAbstract (sommario):
Abstract Given the particularity, significance, and complexity of particle migration behavior in fine silt sand hydrate reservoirs, the agglomeration and plugging behavior of free fine particles are mainly studied. Based on the discrete element method (DEM) and computational fluid dynamics (CFD), the DEM-CFD coupled 3D wellbore sand production numerical model is established and verified. The DEM module divides the reservoir particles into coarse and fine components according to the actual particle size distribution, and assigns adhesive and non-adhesive rolling resistance linear models, respectively. The CFD module uses the finite volume method to solve the incompressible Darcy flow in coarse grids. The results show that the DEM-CFD coupled numerical model established can effectively simulate the phenomenon of fine particle agglomeration during particle migration; Compared with the condition without particle agglomeration, fine particle agglomeration can lead to lower wellbore sand production and more severe pore blockage and permeability loss in the surrounding reservoir; The influences of different production and reservoir parameters such as flow rate, porosity and mud content on the variation of wellbore sand production and reservoir permeability under the condition of fine particle agglomeration is further determined, and relevant production measures and suggestions are put forward. The research results help to clarify the sand production mechanism and characteristics of fine silt sand reservoirs and are expected to provide theoretical and technical support for the efficient and safe development of natural gas hydrate resources in fine silt sand reservoirs.
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Pisitsungkakarn, Sumol Sae Heng. "An Inlet Area for Particle Mixing in a Two-Dimensional Fluidized Bed Using a CFD-DEM Model". Applied Mechanics and Materials 467 (dicembre 2013): 367–73. http://dx.doi.org/10.4028/www.scientific.net/amm.467.367.
Testo completoAbstract (sommario):
Fluidized beds are widely used in many industries since they are effective in mixing process. The distinct element method (DEM) has recently received more attention for investigating the phenomena of multiphase flow because the technique is effective in gathering detailed information on the complex phenomena without physically disturbing the flows. A CFD-DEM model has been developed for calculating the minimum fluidization velocity and particle mixing in a two-dimensional fluidized bed. In this research, the inlet area on the particle mixing was investigated. From the result, it was indicated that the developed CFD-DEM model was performed adequately in predicting the phenomena in a two dimensional fluidized bed. The minimum fluidization velocity predicted by the developed model agreed well with the theory and correlation of Grace. Based on Lacey mixing index, it was found that the mixing index increased with an increase in time and superficial gas velocity. In addition, the inlet area of 20% gave a good mixing.
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Fernando, Warnakulasooriya Dinoja Sammani, e Jamal Naser. "Eularian–Eularian Model for Agglomeration Behavior of Combusted Iron Particles". Applied Sciences 14, n. 17 (4 settembre 2024): 7829. http://dx.doi.org/10.3390/app14177829.
Testo completoAbstract (sommario):
Direct reduction of iron (DRI) technology in fluidized beds has been identified as a promising approach due to its environmental benefits over other methods. Nevertheless, the process of iron particle sintering in the DRI approach poses a significant obstacle to its advancement. The present work investigated the phenomenon of agglomeration in fine iron particles across various temperatures and with multiple sintering force models of different intensities of solid bridge force. The study utilized a simple but comprehensive and cost-effective CFD model developed using the Eularian–Eularian two-fluid model. The model was explicitly incorporated with user-defined subroutines for the solid phase, while the gas phase was modeled with AVL Fire advance simulation software. The solid bridge force between solid particles was modeled as the inter-particle cohesive force. The model was validated with the experimental results and results from another CFD-DEM model for the same experiment. High temperatures with increased sintering forces were observed to have the most impact on the iron particle agglomeration, while the gas’s superficial velocity had a minimal effect on it. The predictions of this model closely align with the CFD-DEM model results, providing sufficient reliability to implement this model on a large scale.
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Ding, Tianxiang, Xuyan Hou, Man Li, Guangyu Cao, Jixuan Liu, Xianlin Zeng e Zongquan Deng. "Investigation on Computing Method of Martian Dust Fluid Based on the Energy Dissipation Method". International Journal of Aerospace Engineering 2020 (23 maggio 2020): 1–13. http://dx.doi.org/10.1155/2020/2370385.
Testo completoAbstract (sommario):
In this paper, an initiative Martian dust fluid simulating research based on the energy dissipation method was developed to simulate the deposition process of Martian dust fluid which was caused by surface adhesion between particles and Martian rovers. Firstly, an energy dissipation model of particles based on the Discrete Element Method (DEM) was established because of the characteristics of Martian dust particles such as tiny size and viscoelasticity. This model is based on the existing DMT model to analyze the collision deposition of dust fluid particles, including particle-spacecraft collision and particle-particle collision. Secondly, this paper analyzed the characteristics of particles after their first collision, then, established the stochastic model of critical wind speed for the particle deposition process. Finally, a series of simulations of the Martian dust fluid particle deposition process were done based on DEM-CFD. The results verified the accuracy of the energy dissipation model and the stochastic model, which could also verify the feasibility and effectiveness of the computing method of Martian dust fluid based on the DEM-CFD technology.
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Azadi Tinat, Mohammad Reza, Murali Uddagiri, Ingo Steinbach e Inmaculada López-Galilea. "Numerical Simulations to Predict the Melt Pool Dynamics and Heat Transfer during Single-Track Laser Melting of Ni-Based Superalloy (CMSX-4)". Metals 13, n. 6 (8 giugno 2023): 1091. http://dx.doi.org/10.3390/met13061091.
Testo completoAbstract (sommario):
Computational Fluid Dynamics (CFD) simulations are used in this work to study the dynamic behavior of the melt pool and heat transfer during the single-track laser melting process of a nickel-based superalloy (CMSX-4). To include the effects of powder inhomogeneities and obtain a realistic distribution of the powder layer on the bed chamber, the CFD model is coupled with a Discrete Element Method (DEM) solver. The coupled model is implemented in the open-source software package OpenFOAM. In the CFD model’s governing equations, some key physical mechanisms, such as the Marangoni effect and recoil pressure, are considered. With the help of the coupled CFD-DEM model, we have investigated the effect of key process parameters, such as laser power, scanning speed of the laser, powder size, and powder shape, on the size and homogeneity of the melt pool. From the simulation results, it was discovered that high laser power and slow scanning speed create a deep and narrow keyhole that leads to porosity. In contrast, balling defects are found to be caused by a small melt pool obtained from fast scanning speeds and inadequate laser power.
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Romano, Francis, Edouard Izard e Pascal Fede. "Mechanical Analysis of the Forces Involved in a Pilot-Scale Blast Furnace Raceway Formation by Means of CFD/DEM Simulations". Processes 12, n. 4 (22 marzo 2024): 637. http://dx.doi.org/10.3390/pr12040637.
Testo completoAbstract (sommario):
The CFD/DEM approach was used for investigating the forces playing a role in a furnace raceway formation and stability. The configuration is an actual pilot-scale hot blast furnace filled only with coke particles. In such a system, the raceway was unstable, with successively a growing phase and a collapse. The CFD/DEM numerical simulations were coupled with a core-shrinking model to mimic coke particle combustion. However, the kinetic reactions and heat transfers were not numerically predicted. Instead, the characteristic combustion timescale of one coke particle was imposed, and the combustion zone was adjusted to match the global combustion measured in the pilot-scale experiment. The results showed that the standard contact model was not enough to resist the pressure exerted by the granular weight on the raceway. However, the addition of a cohesive force, through the Johnson-Kendall-Roberts (JKR) model, allowed the qualitative reproduction of the gas pressure fluctuations and the collapse cycles in accordance with the experiment. A sensitivity analysis of the flow rate showed that CFD/DEM is able to reproduce quantitatively the time between two collapses, as observed in the experiment. Predicted raceway size and shapes are also in agreement with the experimental observations in the range of investigated parameters.
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Zhou, Ling, Lingjie Zhang, Ling Bai, Weidong Shi, Wei Li, Chuan Wang e Ramesh Agarwal. "Experimental study and transient CFD/DEM simulation in a fluidized bed based on different drag models". RSC Advances 7, n. 21 (2017): 12764–74. http://dx.doi.org/10.1039/c6ra28615a.
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Xie, Jun, Wenqi Zhong, Yingjuan Shao e Kaixi Li. "Coupling of CFD-DEM and reaction model for 3D fluidized beds". Powder Technology 353 (luglio 2019): 72–83. http://dx.doi.org/10.1016/j.powtec.2019.05.001.
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Alobaid, Falah, Jochen Ströhle e Bernd Epple. "Extended CFD/DEM model for the simulation of circulating fluidized bed". Advanced Powder Technology 24, n. 1 (gennaio 2013): 403–15. http://dx.doi.org/10.1016/j.apt.2012.09.003.
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Wang, Xiaodong, Kai Chen, Ting Kang e Jie Ouyang. "A Dynamic Coarse Grain Discrete Element Method for Gas-Solid Fluidized Beds by Considering Particle-Group Crushing and Polymerization". Applied Sciences 10, n. 6 (12 marzo 2020): 1943. http://dx.doi.org/10.3390/app10061943.
Testo completoAbstract (sommario):
The discrete element method (DEM) coupled with computational fluid dynamics (CFD) is used extensively for the numerical simulation of gas-solid fluidized beds. In order to improve the efficiency of this approach, a coarse grain model of the DEM was proposed in the literature. In this model, a group of original particles are treated as a large-sized particle based on the initial particle distribution, and during the whole simulation process the number and components of these particle-groups remain unchanged. However, collisions between particles can lead to frequent crushing and polymerization of particle-groups. This fact has typically been ignored, so the purpose of this paper is to rationalize the coarse grain DEM-CFD model by considering the dynamic particle-group crushing and polymerization. In particular, the effective size of each particle-group is measured by a quantity called equivalent particle-group diameter, whose definition references the equivalent cluster diameter used by the energy-minimization multi-scale (EMMS) model. Then a particle-group crushing criterion is presented based on the mismatch between the equivalent diameter and actual diameter of a particle-group. As to the polymerization of two colliding particle-groups, their velocity difference after collision is chosen as a criterion. Moreover, considering the flow heterogeneity induced by the particle cluster formation, the EMMS drag force model is adopted in this work. Simulations are carried out by using a finite volume method (FVM) with non-staggered grids. For decoupling the Navier-Stokes equations, the semi-implicit method for pressure linked equations revised (SIMPLER) algorithm is used. The simulation results show that the proposed dynamic coarse grain DEM-CFD method has better performance than the original one.
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Li, Ziyi, e Wanqiang Song. "Coupled CFD-DEM simulation of submarine landslide movement behavior". Journal of Physics: Conference Series 2599, n. 1 (1 settembre 2023): 012030. http://dx.doi.org/10.1088/1742-6596/2599/1/012030.
Testo completoAbstract (sommario):
Abstract Submarine landslide is a common disaster geological phenomenon in the ocean, which can be destructive to underwater infrastructure. Therefore, it is necessary to simulate the evolutionary behavior of submarine viscous landslides. In this paper, computational fluid dynamics (CFD) and discrete element method (DEM) are used to establish the fluid-solid coupling model of water-particle interaction. Firstly, the inter-particle cohesion model is introduced to train the coupled CFD-DEM analysis of the kinematic evolution process, and at the same time, two typical cases are carried out to verify the analysis. In the experimental simulation, the kinematic and morphological characteristics of the submarine landslide were simulated considering the viscous effect and initial velocity of the landslide, and the influence mechanism of the landslide motion and evolution process was investigated in depth. The results show that the coupled method can better simulate the motion of submarine landslide, and the viscous effect of the landslide has a significant influence on its kinematic and morphological characteristics, and the initial velocity also significantly affects the evolution and distribution characteristics of the particle flow field of each part of the landslide in the process of motion. This study is important for the simulation and effective prediction of the kinematic evolution process of real submarine landslides.
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Zhang, Hong, Bang Zhang, Can Wu e Kun Chen. "Macro and micro analysis on coal-bearing soil slopes instability based on CFD-DEM coupling method". PLOS ONE 16, n. 9 (17 settembre 2021): e0257362. http://dx.doi.org/10.1371/journal.pone.0257362.
Testo completoAbstract (sommario):
By combining the discrete element method (DEM) with computational fluid dynamics (CFD), this study proposes a three-dimensional CFD–DEM fluid–solid coupling microscopic computational model for analyzing the micromechanisms of instability and failure in a coal-bearing soil slope during rainfall. The CFD–DEM fluid–solid coupling model indicated that the main failure mode of the coal-bearing soil slopes was rainwater washing, and the slope sliding surface was predicted as an approximately linear segment. The adaptability of this numerical method was verified by comparing its results with those of rain-washed slopes in an outdoor model test. Rainfall changed the microscopic parameters such as the force chain, coordination number, and porosity of the slope soil particles. The porosity of the slope’s top particles increased from 0.35 in the initial state to 0.80 in the unstable state. This change was directly related to the macroscopic mechanics of the slope soil. By analyzing the changes in the microscopic parameters of the particles, the failure evolution law of the coal-bearing soil slopes during rainfall was explored from a microscopic perspective. This study not only provides a theoretical basis for the protection design and construction of coal-bearing soil slopes in the region but can also analyze macroscopic mechanical laws of discrete media from a micro–macro perspective in geotechnical engineering.
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Tokarczyk, Jarosław, Daniel Kowol, Kamil Szewerda e Piotr Matusiak. "Virtual Prototyping of Bulk Material Preparation Devices in Mining Using Multiphysics Simulations". Applied Sciences 14, n. 13 (5 luglio 2024): 5903. http://dx.doi.org/10.3390/app14135903.
Testo completoAbstract (sommario):
This paper presents the process of virtual prototyping of bulk material preparation devices in mining using numerical simulations of multi-physics phenomena. The discrete element method (DEM), meshless method (MFree), and computational fluid dynamics (CFD) were used in the calculation process. The importance of the extraction process and the practical application of DEM in various industries are discussed. The main contact models between particles and how structural material wear is modelled in DEM are presented. The structure of the computational models in DEM and CFD environments is presented. For the validation of the bulk material computational model, bench tests were carried out to determine the material properties (aggregate: five grades, 0–16 mm; coal concentrate: five grades, 2–32 mm; and so-called raw coal, grade 2–8 mm). The bulk density and angle of natural repose were measured, along with determination of the internal and external friction coefficients. Simulations corresponding to the laboratory tests were carried out. Numerical calculations were carried out for the side chute (results—velocities of the particles, compressive forces in the particles, determination of the wearing process) and for the coke classification line (two lines were assessed according to different aggregate sizes and densities of the bulk material). These multi-physics calculations required a combination of DEM-MFree and DEM-CFD methods. Based on the obtained results, it was possible to evaluate the performance and efficiency of the assessed machines.
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Zhang, Fengshou, Haiyan Zhu, Hanguo Zhou, Jianchun Guo e Bo Huang. "Discrete-Element-Method/Computational-Fluid-Dynamics Coupling Simulation of Proppant Embedment and Fracture Conductivity After Hydraulic Fracturing". SPE Journal 22, n. 02 (6 febbraio 2017): 632–44. http://dx.doi.org/10.2118/185172-pa.
Testo completoAbstract (sommario):
Summary In this paper, an integrated discrete-element-method (DEM)/computational-fluid-dynamics (CFD) numerical-modeling work flow is developed to model proppant embedment and fracture conductivity after hydraulic fracturing. Proppant with diameter from 0.15 to 0.83 mm was modeled as a frictional particle assembly, whereas shale formation was modeled as a bonded particle assembly by using the bonded-particle model in PFC3D (Itasca Consulting Group 2010). The mechanical interaction between proppant pack and shale formation during the process of fracture closing was first modeled with DEM. Then, fracture conductivity after the fracture closing was evaluated by modeling fluid flow through the proppant pack by use of DEM coupled with CFD. The numerical model was verified by laboratory fracture-conductivity experiment results and the Kozeny-Carman equation. The simulation results show that the fracture conductivity increases with the increase of proppant concentration or proppant size, and decreases with the increase of fracture-closing stress or degree of shale hydration; shale-hydration effect was confirmed to be the main reason for the large amount of proppant embedment.
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Chen, Meng, Zhao Chen, Yaping Tang e Malin Liu. "CFD-DEM simulation of particle coating process coupled with chemical reaction flow model". International Journal of Chemical Reactor Engineering 19, n. 4 (9 marzo 2021): 393–413. http://dx.doi.org/10.1515/ijcre-2020-0241.
Testo completoAbstract (sommario):
Abstract Particle coating process, one of the main methods to improve the particle properties, is widely used in industrial production and pharmaceutical industry. For the scale up and optimization of this process, a mechanistic and detailed study is needed or numerical simulation as an alternative way. Decomposition of substances usually involves multiple chemical reactions and produces multiple substances in the actual chemical reaction. In the study, a chemical reaction flow (CRF) model has been established based on kinetic mechanism of elementary reaction, the theory of molecular thermodynamics and the sweep theory. It was established with the comprehensive consideration of the decomposition of substances, deposition process, adhesion process, desorption process, hydrogen inhibition, and clearance effect. Then the CFD-DEM model was coupled with CRF model to simulate particle coating process by FB-CVD method, and the CFD-DEM-CRF coupling model was implemented in the software Fluent-EDEM with their user definition function (UDF) and application programming interface (API). The coating process in the spouted bed was analyzed in detail and the coating behavior under different conditions were compared at the aspects of CVD rate, coating efficiency, particle concentration distribution, particle mixing index and gas concentration distribution. It is found that the average CVD rate is 6.06 × 10−4 mg/s when the inlet gas velocity is 11 m/s and bed temperature is 1273 K, and simulation result agrees with the experimental result well. Average CVD rate and coating efficiency increase with temperature increasing, but decrease acutely with mass fraction of injected hydrogen increasing. The CFD-DEM-CRF coupling model can be developed as a basic model for investigating particle coating process in detail and depth and can provide some guidance for the operating conditions and parameters design of the spouted bed in the real coating process.
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Kavand, Mohammad. "Multiscale CFD-DEM model for the CO2 gasification reaction of carbon anode". Fuel 297 (agosto 2021): 120692. http://dx.doi.org/10.1016/j.fuel.2021.120692.
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Deglon, David, Evan Smuts e Chris Meyer. "A Coupled CFD-DEM Model for Simulating the Rheology of Particulate Suspensions". Progress in Computational Fluid Dynamics, An International Journal 1, n. 1 (2016): 1. http://dx.doi.org/10.1504/pcfd.2016.10001210.
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Smuts, Evan M., David A. Deglon e Chris J. Meyer. "A coupled CFD-DEM model for simulating the rheology of particulate suspensions". Progress in Computational Fluid Dynamics, An International Journal 17, n. 5 (2017): 290. http://dx.doi.org/10.1504/pcfd.2017.086340.
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Chu, Kaiwei, Jiang Chen e Aibing Yu. "Applicability of a coarse-grained CFD–DEM model on dense medium cyclone". Minerals Engineering 90 (maggio 2016): 43–54. http://dx.doi.org/10.1016/j.mineng.2016.01.020.
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Farivar, Foad, Hu Zhang, Zhao F. Tian e Anshul Gupte. "CFD-DEM -DDM Model for Spray Coating Process in a Wurster Coater". Journal of Pharmaceutical Sciences 109, n. 12 (dicembre 2020): 3678–89. http://dx.doi.org/10.1016/j.xphs.2020.09.032.
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Foroutan, Talat, e Ali Asghar Mirghasemi. "CFD-DEM model to assess stress-induced anisotropy in undrained granular material". Computers and Geotechnics 119 (marzo 2020): 103318. http://dx.doi.org/10.1016/j.compgeo.2019.103318.
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KHAMITOV, F., A. KASSENOV e A. SARSENOVA. "SAND PRODUCTION CONTROL IN KAZAKHSTAN OILFIELDS USING A MULTIPHASE CFD-DEM MODEL". Neft i Gaz 144, n. 6 (15 dicembre 2024): 192–204. https://doi.org/10.37878/2708-0080/2024-6.12.
Testo completoAbstract (sommario):
Sand production is a significant issue in Kazakhstan’s oil and gas fields with unconsolidated formations involving the multiphase flow (water-oil) of reservoir fluids and solid particles. The sand control approach includes the multiscale mechanisms of sand production, particularly fluid flow and particle movement. This study investigates sand production and oil recovery in multiphase flow using coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) modeling on a cubic sandstone sample, focusing on a traditional vertical producing well. The weak sandstone formations model was used to simulate sand particle extraction from Object 2 of the Karazhanbas oilfield. The four cases with different sieve sizes and one without sieve were simulated. The sieve sizes were chosen based on sample particle size distribution (PSD). The transient sand production behavior in simulations without a sieve was observed and showed qualitative agreement with the literature data. Sieve size significantly impact sand production, with smaller sieves reducing extraction rates. Effective sand control was achieved with sieve diameters up to 3d50 (average particle diameter), beyond which further increases did not prevent sand production. The sieve implementation had a multiplicative effect: controlling sand production and improving the oil recovery factor by up to 21%.
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Saeedrashed, Younis Saida, e Ali Cemal Benim. "A computational investigation of the hydrodynamics of the Badush dam in northern Iraq". MATEC Web of Conferences 240 (2018): 04009. http://dx.doi.org/10.1051/matecconf/201824004009.
Testo completoAbstract (sommario):
A computational analysis of the hydrodynamics of the Badush dam in Iraq is presented, which is planned to be reconstructed as a repulse dam, to prevent the Mosul city, in case of a failure of the Mosul dam. Computational Fluid Dynamics (CFD) is applied in combination with Geometric Information System (GIS) and Digital Elevation Model (DEM). In the first part of the study, a hydrologic study of a possible Mosul dam failure is performed, predicting the important parameters for a possible flooding of Mosul city. Here, a two-dimensional, depth-averaged shallow water equations are used to formulate the flow. Based on GIS and DEM, the required reservoir size and the water level of the Badush dam are predicted, for its acting as a repulse dam. Subsequently, a computational model of the reconstructed Badush dam is developed, combining the proposed construction with the local geographic topology to achieve a perfect fit. Finally, the water flow through the bottom outlets and stilling basin of the proposed dam is calculated by an unsteady, three-dimensional CFD analysis of the turbulent, free-surface flow. The CFD model is validated by comparing the predictions with measurements obtained on a physical model, where a quite satisfactory agreement is observed.
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Hou, Jiawen, Dongdong Wang, Fan Li, Hongxia Zhao, Jiangtao Zhang, Lijie Jin, Chu-an Zhang, Dening Xiang, Ya-nan Chen e Xuehong Wu. "Study on heat and mass transfer characteristics in drying process of drum dryer based on the DEM-CFD coupled method". Thermal Science, n. 00 (2024): 177. http://dx.doi.org/10.2298/tsci240419177h.
Testo completoAbstract (sommario):
In order to analyze the heat and mass transfer characteristics of cut tobacco in a horizontal drum dryer, the discrete element method (DEM) was used to calculate the particle collision model and DEM-CFD coupled heat transfer model. With the increase of the rotating speed, the mixing degree gradually increases, and when the rotating speed is 16 rpm, the mixing degree is higher. When the heat flux of EDEM-CFD coupling is 0.2 W-1W, the particle temperature will gradually increase and tend to a fixed value. The residence time of the material has a great influence on the drying quality of the material particles. If the residence time is too short, the heat of the material will be uneven, and if the residence time of the material is too long, the damage of the material particles will increase, increased crushing rate.
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Chen, Liwei, Chunhua Chen, Qingchun Fan, Zihui Yang, Zihao Zheng e Jianye Wang. "Migration Simulation of Radioactive Soil Particles in the Atmospheric Environment Using CFD-DEM Coupled with Empirical Formulas". Science and Technology of Nuclear Installations 2021 (29 maggio 2021): 1–10. http://dx.doi.org/10.1155/2021/6690451.
Testo completoAbstract (sommario):
Radioactive particle migration from the soil surface is an unignorable factor for the radioactive material distribution prediction after a nuclear accident, especially for the decision support of radioactive disposal. Considering the continuous emission, collision, and reattachment of radioactive particles, a creative simulation method with a coupled model was proposed, which combines an empirical model and the CFD-DEM method, and was established to simulate the secondary emission and motion of radioactive particles. The source term of the radioactive particles is estimated by an empirical model as the input of the CFD-DEM. Regarding the characteristics of the particle motion, the spout-fluidized bed simulation by the coupled model is consistent with the referred simulation results and experimental data, which validates the correctness of this model. The coupling model was applied to simulate the radioactive particle distribution and migration on the nonconfined backward facing step (NBFS). The simulation reveals that the distribution features and migration flux of the radioactive particles can be estimated in detail by the proposed model, which can help to provide more actual information for radioactive disposal after nuclear accidents.
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Liu, Daoyin, Changsheng Bu e Xiaoping Chen. "Development and test of CFD–DEM model for complex geometry: A coupling algorithm for Fluent and DEM". Computers & Chemical Engineering 58 (novembre 2013): 260–68. http://dx.doi.org/10.1016/j.compchemeng.2013.07.006.
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Fernandes, Célio, Luís L. Ferrás e Alexandre Afonso. "A Primer on CFD-DEM for Polymer-Filled Suspensions". Applied Sciences 13, n. 4 (14 febbraio 2023): 2466. http://dx.doi.org/10.3390/app13042466.
Testo completoAbstract (sommario):
This work reports on an evaluation of the computational fluid dynamics–discrete element method (CFD-DEM) numerical approach to study the behavior of polymer-filled suspensions in a parallel-plate rheometer. For this purpose, an open-source CFD-DEM solver is used to model the behavior of such suspensions considering different particle volume fractions and different types of fluid rheology. We first validate the numerical approach for the single-phase flow of the continuum phase (fluid phase) by comparing the fluid’s azimuthal velocity and shear stress components obtained from the open-source solver against the analytical expressions given in cylindrical coordinates. In addition, we compare the numerical torque given by the numerical procedure with analytical expressions obtained for Newtonian and power law fluids. For both cases, there is a remarkable agreement between the numerical and analytical results. Subsequently, we investigated the effects of the particle volume fraction on the rheology of the suspension. The numerical results agree well with the experimentally measured ones and show a yield stress phenomenon with the increase of the particle volume fraction.
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Wu, Tao, Fatang Li, Qingting Liu, Jiahui Ren, Jibai Huang e Zhanji Qin. "Numerical Simulation and Analysis of the Impurity Removal Process of a Sugarcane Chopper Harvester Based on a CFD–DEM Model". Agriculture 14, n. 8 (18 agosto 2024): 1392. http://dx.doi.org/10.3390/agriculture14081392.
Testo completoAbstract (sommario):
The cleaning system is a critical component of the sugarcane chopper harvester, facing challenges such as high impurity rate, elevated power consumption, and an inadequate understanding of the cleaning mechanism. This study aims to simulate the process of removing extraneous matter (represented by sugarcane leaves) from the cleaning system by employing a coupling approach of computational fluid dynamics (CFD) and the discrete element method (DEM) to determine the speed of the extractor fan. Initially, a CFD model was established to analyze the airflow field within the extractor, and its accuracy was verified on a test bench for the cleaning system. Subsequently, a DEM model was developed for sugarcane billets and leaves, which was then integrated with the CFD model to form a gas–solid coupling model. The efficacy of this integrated model was confirmed through experimental measurements of impurity rate. Furthermore, a ternary quadratic regression orthogonal combination design was utilized in the gas–solid coupling simulation to assess the impacts of feed rate, leaf–stalk ratio, and extractor fan speed on impurity rate. Finally, the extractor fan speeds were obtained for various feed rates and leaf–stalk ratios under impurity rates of 5%, 6%, 7%, and 8%. This research can guide in controlling the extractor fan speed during sugarcane chopper harvester field operations and can serve as a foundation for extractor fan design.
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Nguyen, Thanh Trung, e Buddhima Indraratna. "Experimental and numerical investigations into hydraulic behaviour of coir fibre drain". Canadian Geotechnical Journal 54, n. 1 (gennaio 2017): 75–87. http://dx.doi.org/10.1139/cgj-2016-0182.
Testo completoAbstract (sommario):
Over many decades, natural fibre bundles have been widely used for drainage and filtration applications because of their favourable hydraulic conductivity and abundance in Asian countries. In recent times, natural (biodegradable) coir and jute drains, which are environmentally friendly, have been considered in lieu of conventional geosynthetic wick drains for soft clay consolidation in Australian coastal regions. However, there is a lack of a computational framework to predict the hydraulic behaviour of fibre drains on the basis of micromechanical (fabric) characteristics. Employing computational fluid dynamics (CFD) coupled with the discrete element method (DEM) to model the hydraulic behaviour of fibrous materials has shown promise in an earlier 2016 study by Nguyen and Indraratna, which considered an idealized parallel arrangement of fibres for simplicity. This paper aims to broaden the application of the coupled CFD–DEM technique to real fibres (coconut coir) considering both nontwisted and twisted fibre bundles that have more complex porous structure. The hydraulic conductivity determined from the numerical approach is validated with the experimental results, and also compared with the analytical prediction based on the conventional Kozeny–Carmen (KC) approach. The current study shows that the CFD–DEM technique can capture well the fluid flow characteristics of a nonuniform fibrous structure, including dense twisted coir bundles.
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Zhang, Yinhang, Xiuhua Men, Shuai Wang, Xiuli Fu e Liwen Chen. "CFD-DEM Study of Pleated Filter Plugging Process Based on Porous Media Model". Machines 10, n. 10 (26 settembre 2022): 862. http://dx.doi.org/10.3390/machines10100862.
Testo completoAbstract (sommario):
The pneumatic conveying process of fine particles through filters was studied by CFD-DEM simulation method. The porous media model and porous structure were used to simulate the airflow state and the blocking effect of fine particles when they flowed through the filter. Under different particle feed rates and initial particle velocities, the effects of the plugging rate and settling velocity in pleated filters were analyzed, and the effect of particle deposition height on fluid zone was studied. The results showed that particles should avoid the feed rate of 250–750 g/s and choose the initial particle velocity of 3–6 m/s to achieve lower plugging rate and faster settling velocity. The position of the filter should avoid the particle inlet to avoid the increase of non-uniformity. Timely cleaning of particles in the filter box can improve the filtering performance.