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Journal articles on the topic 'Eulerian-granular model'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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1

Lee, T. G., and S. W. Shin. "DEVELOPMENT OF EULERIAN-GRANULAR MODEL FOR NUMERICAL SIMULATION MODEL OF PARTICULATE FLOW." Journal of computational fluids engineering 20, no. 2 (June 30, 2015): 46–51. http://dx.doi.org/10.6112/kscfe.2015.20.2.046.

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2

Wang, Jiao Jiao, Qiang Zhu, Fan Zhang, Da Quan Li, and You Feng He. "Investigation on Liquid Segregation during Rheo-Casting Process Based on Eulerian-Granular Multiphase Model." Solid State Phenomena 256 (September 2016): 113–18. http://dx.doi.org/10.4028/www.scientific.net/ssp.256.113.

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A crucial problem concerned with the semi-solid forming process is the liquid segregation phenomena during shape formation, especially for rheo-casting process. Liquid segregation occurs due to the separation phenomena of the solid grain and the liquid phase. In this work, using commercial finite element software, the liquid segregation during rheo-casting process was numerically investigated by Eulerian-granular multiphase model based on the comparable results of single phase model, Eulerian-granular two-phase and three-phase model, along with Eulerian-granular DDPM three-phase model. In the study, solid grains and liquid phases were regarded as rigid material and non-Newtonian fluid at microscale, separately. This validation was experimentally proved and also compared to the proposed relationship of power law, Herschel-Bulkley model with yield stress at macroscale.
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3

Wang, Chun, Guanlin Ye, Xiannan Meng, Yongqi Wang, and Chong Peng. "A Eulerian–Lagrangian Coupled Method for the Simulation of Submerged Granular Column Collapse." Journal of Marine Science and Engineering 9, no. 6 (June 3, 2021): 617. http://dx.doi.org/10.3390/jmse9060617.

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A two-fluid Eulerian–Lagrangian coupled model is developed to investigate the complex interactions between solid particles and the ambient water during the process of submerged granular column collapse. In this model, the water phase is considered to be a Newtonian fluid, whereas the granular column is modeled as an elastic–perfectly plastic material. The water flow field is calculated by the mesh-based Eulerian Finite Volume Method (FVM), with the free surface captured by the Volume-of-Fluid (VOF) technique. The large deformation of the granular material is simulated by the mesh-free, particle-based Lagrangian Smoothed Particle Hydrodynamics method (SPH). Information transfer between Eulerian nodes and Lagrangian particles is performed by the aid of the SPH interpolation function. Both dry and submerged granular column collapses are simulated with the proposed model. Experiments of the submerged cases are also conducted for comparison. Effects of dilatancy (compaction) of initially dense (loose) packing granular columns on the mixture dynamics are investigated to reveal the mechanisms of different flow regimes. Pore water pressure field and granular velocity field are in good agreement between our numerical results and experimental observations, which demonstrates the capability of the proposed Eulerian–Lagrangian coupled method in dealing with complex submerged water–granular mixture flows.
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4

Han, Xin Feng, Jian Long Li, and Ning Xu. "CFD Simulation of the Fluidized Bed Applied in the Synthesis of Benzene Series Organosilicon." Advanced Materials Research 753-755 (August 2013): 2663–66. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.2663.

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The mathematical model of gas-solid flow 2D fluidized bed was established. The CFD simulation was carried out with commercial software FLUENT6.3 by using Eulerian-Eulerian multiphase models, based on the kinetic theory of granular flow and PC-SIMPLE algorithm. In order to provide a basis on optimizing the operating conditions of the fluidized bed applied in benzene series organosilicon reactor, the processes of bubble formation, growth and disappearance under different cases were analyzed.
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Zhang, Yang, Changsong Wu, Xiaosi Zhou, Yuanming Hu, Yuan Wang, and Bin Yang. "A Numerical Study of Aeolian Sand Particle Flow Incorporating Granular Pseudofluid Optimization and Large Eddy Simulation." Atmosphere 11, no. 5 (April 29, 2020): 448. http://dx.doi.org/10.3390/atmos11050448.

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A numerical investigation of aeolian sand particle flow in atmospheric boundary layer is performed with a Eulerian–Eulerian granular pseudofluid model. In this model, the air turbulence is modelled with a large eddy simulation, and a kinetic–frictional constitutive model incorporating frictional stress and the kinetic theory of granular flow is applied to describe the interparticle movement. The simulated profiles of streamwise sand velocity and sand mass flux agree well with the reported experiments. The quantitative discrepancy between them occurs near the sand bed surface, which is due to the difference in sand sample, but also highlights the potential of the present model in addressing near-surface mass transport. The simulated profiles of turbulent root mean square (RMS) particle velocity suggest that the interparticle collision mainly account for the fluctuation of sand particle movement.
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6

Hilmee, M. I., Mohan Sinnathambi Chandra, Saravanan Karuppanan, M. Fadhil, and Mohd Rizal Lias. "Effects of Different Granular Viscosity Models on the Bubbling Fluidized Bed - A Numerical Approach." Applied Mechanics and Materials 393 (September 2013): 857–62. http://dx.doi.org/10.4028/www.scientific.net/amm.393.857.

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Kinetic Theory of Granular Flow (KTGF) has been successfully incorporated and widely implemented in the Eulerian simulation models in many multiphase cases. The KTGF theory involves many parameters and is applied in the multiphase simulation for the purpose of hydrodynamic properties modeling of the granular phase. This paper is focused on granular viscosity which is a parameter in the KTGF that incorporates three different viscosities arising from the inter-phase and intra phases interaction in a bubbling fluidized bed (BFB). The 2D BFB model of 0.2 m width and 0.8 m length having a 13-hole orifice plate has been modeled for this purpose. The model was constructed using Gambit software version 2.4.6 and then simulated using ANSYS Fluent version 14. Two models of granular viscosity, namely Syamlal-Obrien model and Gidaspow model, were compared based on its effect to the pressure drop and bed expansion of the BFB. The results depicted that the simulation based on Syamlal-Obrien model tends to produce larger bubbles and contributing to a higher pressure drop across the distributor plate as compared to the Gidaspow model.
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7

Wu, Ze-Xiang, Hui Ji, Jian Han, and Chuang Yu. "Numerical modelling of granular column collapse using coupled Eulerian–Lagrangian technique with critical state soil model." Engineering Computations 36, no. 7 (August 12, 2019): 2480–504. http://dx.doi.org/10.1108/ec-08-2018-0358.

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Purpose Current modellings of granular collapse are lack of considering the effect of soil density. This paper aims to present a numerical method to analyse the collapse of granular column based on the critical-state soil mechanics. Design/methodology/approach In the proposed method, a simple critical-state based constitutive model is first adopted and implemented into a finite element code using the coupled Eulerian–Lagrangian technique for large deformation analysis. Simulations of column collapse with various aspect ratios are then conducted for a given initial soil density. The effect of aspect ratio on the final size of deposit morphology, dynamical collapse profiles and the stable region is discussed comparing to experimental results. Moreover, complementary simulations with various initial soil densities on each aspect ratio are conducted. Findings Simulations show that a lower value of initial density leads to a lower final deposit height and a longer run-out distance. The simulated evolutions of kinetic energy and collapsing profile with time by the proposed numerical approach also show clearly a soil density-dependent collapse process. Practical implications To the end, this study can improve the understanding of column collapse in different aspect ratios and soil densities, and provide a computational tool for the analysis of real scale granular flow. Originality/value The originality of this paper is proposed in a numerical approach to model granular column collapse considering the influences of aspect ratio and initial void ratio. The proposed approach is based on the finite element platform with coupled Eulerian–Lagrangian technique for large deformation analysis and implementing the critical-state based model accounting for the effect of soil density.
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8

Favrie, N., and S. Gavrilyuk. "Dynamic compaction of granular materials." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 469, no. 2160 (December 8, 2013): 20130214. http://dx.doi.org/10.1098/rspa.2013.0214.

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An Eulerian hyperbolic multiphase flow model for dynamic and irreversible compaction of granular materials is constructed. The reversible model is first constructed on the basis of the classical Hertz theory. The irreversible model is then derived in accordance with the following two basic principles. First, the entropy inequality is satisfied by the model. Second, the corresponding ‘intergranular stress’ coming from elastic energy owing to contact between grains decreases in time (the granular media behave as Maxwell-type materials). The irreversible model admits an equilibrium state corresponding to von Mises-type yield limit. The yield limit depends on the volume fraction of the solid. The sound velocity at the yield surface is smaller than that in the reversible model. The last one is smaller than the sound velocity in the irreversible model. Such an embedded model structure assures a thermodynamically correct formulation of the model of granular materials. The model is validated on quasi-static experiments on loading–unloading cycles. The experimentally observed hysteresis phenomena were numerically confirmed with a good accuracy by the proposed model.
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9

Chen, Yu Lin, Qing Wang, Cong Cong Liu, and Jian Xin Ge. "Numerical Simulation of the Flow Characteristics of 35t/h Internally Circulating Fluidized Bed." Applied Mechanics and Materials 529 (June 2014): 272–76. http://dx.doi.org/10.4028/www.scientific.net/amm.529.272.

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The gas-solid flow characteristics of the 35t/h oil shale-combustion circulating fluidized bed boiler (Developed by Wangqing Longteng Energy Development Co., Ltd) was simulated using Eulerian-Eulerian model (EEM), which was based on the kinetic theory of granular. The distribution of particle volume fraction and the distribution of particle velocity revealed the mechanism of the internal recirculation flow of particles in the furnace. The simulation results provided a reference for the flow structure optimization of the inner circulating fluidized bed and the enlargement of the inner circulating fluidized bed boiler.
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10

Heng, J., T. H. New, and P. A. Wilson. "On the application of an Eulerian granular model towards dilute phase pneumatic conveying." Powder Technology 327 (March 2018): 456–66. http://dx.doi.org/10.1016/j.powtec.2017.12.069.

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11

Wang, Jing, Guang Qing Yang, Feng Ying, Jing Qin Mu, Wei Gao, and Wei Ying Ding. "The Research on Simulation Model of BF Raceway Based on Kinetic Theory of Granular Flow." Advanced Materials Research 1078 (December 2014): 239–45. http://dx.doi.org/10.4028/www.scientific.net/amr.1078.239.

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Tuyere raceway was known as the "engine" of the blast furnace, which plays a very important role, but it is very difficult to be directly measured and researched, because of limitation of experimental methods. In this paper application of kinetic theory of granular flow,coke particles as a pseudo-fluid, the two-phase raceway model of gas-solid was constructed by used of Eulerian two-fluid theory, and the model was verified correct.
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12

Wang, Hua, Jie Ding, Xian Shu Liu, and Nan Qi Ren. "The Impact of Water Distribution System on the Internal Flow Field of EGSB by Using CFD Simulation." Applied Mechanics and Materials 614 (September 2014): 596–604. http://dx.doi.org/10.4028/www.scientific.net/amm.614.596.

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The internal flow field of EGSB (Expanded Granular Sludge Bed) reactor was investigated by using CFD simulation. A three-dimensional Eulerian–Eulerian two phase (sewage-granular sludge) fluid model was applied to investigate the impact of water distribution system on the internal flow field by considering the ratio α of hole area to reactor area. Results showed that the flow state of sludge granules changed periodically when the sludge bed reached a stabilization stage, and every cycle included two periods (U period and D period), where U stands for up-flow of the granular sludge and D represents down-flow. Keeping the upward-flow velocity of reactor at 3 m/h and reducing ratio α from 1.44% to 0.25%, the flow state of the two periods changed differently and was closely related to the height of reactor. Besides, the ratio α could affect the homogeneity of sludge granules, which could further influence the performance of the reactor. In addition, a validation experiment was conducted to verify the practical applicability of the fluid model, a good relationship between simulation and experiment was discovered, which further confirmed that the ratio α of water distribution system has significant impact on the internal flow field of EGSB.
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13

Nemoda, Stevan, Milica Mladenovic, Milijana Paprika, Dragoljub Dakic, Aleksandar Eric, and Mirko Komatina. "Euler-Euler granular flow model of liquid fuels combustion in a fluidized reactor." Journal of the Serbian Chemical Society 80, no. 3 (2015): 377–89. http://dx.doi.org/10.2298/jsc140130029n.

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The paper deals with the numerical simulation of liquid fuel combustion in a fluidized reactor using a two-fluid Eulerian-Eulerian fluidized bed modeling incorporating the kinetic theory of granular flow (KTGF) to gas and solid phase flow prediction. The comprehensive model of the complex processes in fluidized combustion chamber incorporates, besides gas and particular phase velocity fields? prediction, also the energy equations for gas and solid phase and the transport equations of chemical species conservation with the source terms due to the conversion of chemical components. Numerical experiments show that the coefficients in the model of inter-phase interaction drag force have a significant effect, and they have to be adjusted for each regime of fluidization. A series of numerical experiments was performed with combustion of the liquid fuels in fluidized bed (FB), with and without significant water content. The given estimations are related to the unsteady state, and the modeled time period corresponds to flow passing time throw reactor column. The numerical experiments were conducted to examine the impact of the water content in a liquid fuel on global FB combustion kinetics.
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14

Wang, Qing, Jian Bo Xiao, and Hong Peng Liu. "2D CFD Simulation of Hydrodynamics of the Dense Zone of a 65t/h High-Low Bed CFB." Advanced Materials Research 614-615 (December 2012): 596–99. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.596.

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Gas-solid flow behavior of the bottom zone of a 65t/h High-low bed CFB was simulated using the commercial computational fluid dynamics (CFD) software package Fluent. The Eulerian-Eulerian model (EEM) based on the kinetic theory of granular flow (KTGF) was adopted. This approach treated each phase as continuous separately. The link between the gas and solid phases was through drag model and turbulence model. While the turbulence was simulated by the standard k-ε and mixture multiphase model, the Gidaspow drag model was used to model the interphase interaction. Four phases were set to achieve size distribution in the EEM. Gas and solid flow profiles are obtained for solid velocity, solid volume fraction, pressure, and size distribution. The results show that EEM can predict preferably the internal circulation process of the dense zone high-low bed CFB.
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15

Roberts , Andrew, Recep Kahraman, Desi Bacheva, and Gavin Tabor. "Modelling of Powder Removal for Additive Manufacture Postprocessing." Journal of Manufacturing and Materials Processing 5, no. 3 (August 6, 2021): 86. http://dx.doi.org/10.3390/jmmp5030086.

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A critical challenge underpinning the adoption of Additive Manufacture (AM) as a technology is the postprocessing of manufactured components. For Powder Bed Fusion (PBF), this can involve the removal of powder from the interior of the component, often by vibrating the component to fluidise the powder to encourage drainage. In this paper, we develop and validate a computational model of the flow of metal powder suitable for predicting powder removal from such AM components. The model is a continuum Eulerian multiphase model of the powder including models for the granular temperature; the effect of vibration can be included through appropriate wall boundaries for this granular temperature. We validate the individual sub-models appropriate for AM metal powders by comparison with in-house and literature experimental results, and then apply the full model to a more complex geometry typical of an AM Heat Exchanger. The model is shown to provide valuable and accurate results at a fraction of the computational cost of a particle-based model.
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16

Md Isa, Kamariah, Kahar Osman, Nor Fadzilah Othman, Nik Rosli Abdullah, and Mohd Norhakem Hamid. "A Multiphase Eulerian-Eulerian CFD Simulation of Fluidized Bed Gasification Using Malaysian Low-Rank Coal-Merit Pila." Key Engineering Materials 740 (June 2017): 163–72. http://dx.doi.org/10.4028/www.scientific.net/kem.740.163.

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A multiphase Eulerian- eulerian model integrating the kinetic theory of granular particle (KTGF) was used to simulate the gasification of Malaysian low- rank coal (LRC), Merit- Pila inside a bubbling fluidised bed (BFB) gasifier. The model used includes the bubbling phenomenon and gasificationprocess that occurs inside a BFB gasifier. The gasification process simulated includes drying, heterogeneous reactions of char combustion, devolatilization, water- gas shift reaction, Boudourd reactionand gas phase homogenous reactions. The results from this model are compared to the results of Merit-Pila coal gasification, from which experimental data is available. Comparison of the pressure profile shows good agreement with experimental results. The temperature distribution shows that the maximum temperature is around 1100K which also shows good agreement with experimental values which is 1087K. Besides that, three out of six species mass fraction which is N2, H2 and CH4 produced similar values with experimental values. This shows the simulation conducted was capable to predict the gasification process of Low- rank coal, namely Merit-Pila.
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17

Heng, J., T. H. New, and P. A. Wilson. "Application of an Eulerian granular numerical model to an industrial scale pneumatic conveying pipeline." Advanced Powder Technology 30, no. 2 (February 2019): 240–56. http://dx.doi.org/10.1016/j.apt.2018.10.028.

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18

Nascimento, Suellen Mendonça, F. P. de Lima, Claudio Roberto Duarte, and Marcos Antonio de Souza Barrozo. "Numerical Simulation and Experimental Study of Particle Dynamics in a Rotating Drum with Flights." Materials Science Forum 899 (July 2017): 65–70. http://dx.doi.org/10.4028/www.scientific.net/msf.899.65.

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Rotary dryers are widely used in various industries. Although numerous research efforts have focused on characterizing the dynamics of these equipments, the design of rotating dryers is complex, and theoretical studies are necessary to gain an in-depth understanding of the dynamics of particles in these dryers. This paper aims to investigate the particle dynamic behavior in a rotating drum with flights, based on CFD and experimental results. In the numerical study it was used the Eulerian-Eulerian multiphase model along with the kinetic theory of granular flow. The holdups of solids in the flights were compared with experimental data, using a methodology created specifically for this purpose. The simulated results were in good agreement with the experimental data and the present work has shown that the Eulerian approach has been able to predict the fluid dynamics behavior in different operating conditions.
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19

Tenneti, Sudheer, Mohammad Mehrabadi, and Shankar Subramaniam. "Stochastic Lagrangian model for hydrodynamic acceleration of inertial particles in gas–solid suspensions." Journal of Fluid Mechanics 788 (January 12, 2016): 695–729. http://dx.doi.org/10.1017/jfm.2015.693.

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The acceleration of an inertial particle in a gas–solid flow arises from the particle’s interaction with the gas and from interparticle interactions such as collisions. Analytical treatments to derive a particle acceleration model are difficult outside the Stokes flow regime, but for moderate Reynolds numbers (based on the mean slip velocity between gas and particles) particle-resolved direct numerical simulation (PR-DNS) is a viable tool for model development. In this study, PR-DNS of freely-evolving gas–solid suspensions are performed using the particle-resolved uncontaminated-fluid reconcilable immersed-boundary method (PUReIBM) that has been extensively validated in previous studies. Analysis of the particle velocity variance (granular temperature) equation in statistically homogeneous gas–solid flow shows that a straightforward extension of a class of mean particle acceleration models (drag laws) to their corresponding instantaneous versions, by replacing the mean particle velocity with the instantaneous particle velocity, predicts a granular temperature that decays to zero, which is at variance with the steady particle granular temperature that is obtained from PR-DNS. Fluctuations in particle velocity and particle acceleration (and their correlation) are important because the particle acceleration–velocity covariance governs the evolution of the particle velocity variance (characterized by the particle granular temperature), which plays an important role in the prediction of the core annular structure in riser flows. The acceleration–velocity covariance arising from hydrodynamic forces can be decomposed into source and dissipation terms that appear in the granular temperature evolution equation, and these have already been quantified in the Stokes flow regime using a combination of kinetic theory closure and multipole expansion simulations. From PR-DNS data we show that the fluctuations in the particle acceleration that are aligned with fluctuations in the particle velocity give rise to a source term in the granular temperature evolution equation. This approach is used to quantify the hydrodynamic source and dissipation terms of granular temperature from PR-DNS results for freely-evolving gas–solid suspensions that are performed over a wide range of solid volume fraction ($0.1\leqslant {\it\phi}\leqslant 0.4$), Reynolds number based on the slip velocity between the solid and the fluid phase ($10\leqslant \mathit{Re}_{m}\leqslant 100$) and solid-to-fluid density ratio ($100\leqslant {\it\rho}_{p}/{\it\rho}_{f}\leqslant 2000$). The straightforward extension of drag law models does not give rise to any source in the granular temperature due to hydrodynamic effects. This motivates the development of better Lagrangian particle acceleration models that can be used in Lagrangian–Eulerian formulations of gas–solid flow. It is found that a Langevin equation for the increment in the particle velocity reproduces PR-DNS results for the stationary particle velocity autocorrelation in freely-evolving suspensions. Based on the data obtained from the simulations, the functional dependence of the Langevin model coefficients on solid volume fraction, Reynolds number and solid-to-fluid density ratio is obtained. This new Lagrangian particle acceleration model reproduces the correct steady granular temperature and can also be adapted to gas–solid flow computations using Eulerian moment equations.
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20

Canneto, Giuseppe, Cesare Freda, and Giacobbe Braccio. "Numerical simulation of gas-solid flow in an interconnected fluidized bed." Thermal Science 19, no. 1 (2015): 317–28. http://dx.doi.org/10.2298/tsci121220002c.

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The gas-particles flow in an interconnected bubbling fluidized cold model is simulated using a commercial CFD package by Ansys. Conservation equations of mass and momentum are solved using the Eulerian granular multiphase model. Bubbles formation and their paths are analyzed to investigate the behaviour of the bed at different gas velocities. Experimental tests, carried out by the cold model, are compared with simulation runs to study the fluidization quality and to estimate the circulation of solid particles in the bed.
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21

Schmidt, Robin, and Petr A. Nikrityuk. "Direct numerical simulation of particulate flows with heat transfer in a rotating cylindrical cavity." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369, no. 1945 (June 28, 2011): 2574–83. http://dx.doi.org/10.1098/rsta.2011.0046.

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The purpose of this work was the direct numerical simulation of heat and fluid flow by granular mixing in a horizontal rotating kiln. To model particle behaviour and the heat and fluid flow in the drum, we solve the mass conservation, momentum and energy conservation equations directly on a fixed Eulerian grid for the whole domain including particles. At the same time the particle dynamics and their collisions are solved on a Lagrangian grid for each particle. To calculate the heat transfer inside the particles we use two models: the first is the direct solution of the energy conservation equation in the Lagrangian and Eulerian space, and the second is our so-called linear model that assumes homogeneous distribution of the temperature inside each particle. Numerical simulations showed that, if the thermal diffusivity of the gas phase significantly exceeds the same parameter of the particles, the linear model overpredicts the heating rate of the particles. The influence of the particle size and the angular velocity of the drum on the heating rates of particles is studied and discussed.
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22

Peng, Jian, Wei Sun, Haisheng Han, and Le Xie. "CFD Modeling and Simulation of the Hydrodynamics Characteristics of Coarse Coal Particles in a 3D Liquid-Solid Fluidized Bed." Minerals 11, no. 6 (May 27, 2021): 569. http://dx.doi.org/10.3390/min11060569.

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In this study, a Eulerian-Eulerian liquid-solid two-phase flow model combined with kinetic theory of granular flow was established to study the hydrodynamic characteristics and fluidization behaviors of coarse coal particles in a 3D liquid-solid fluidized bed. First, grid independence analysis was conducted to select the appropriate grid model parameters. Then, the developed computational fluid dynamics (CFD) model was validated by comparing the experimental data and simulation results in terms of the expansion degree of low-density fine particles and high-density coarse particles at different superficial liquid velocities. The simulation results agreed well with the experimental data, thus validating the proposed CFD mathematical model. The effects of particle size and particle density on the homogeneous or heterogeneous fluidization behaviors were investigated. The simulation results indicate that low-density fine particles are easily fluidized, exhibiting a certain range of homogeneous expansion behaviors. For the large and heavy particles, inhomogeneity may occur throughout the bed, including water voids and velocity fluctuations.
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23

Santos, D. A., Irineu Petri Jr., C. R. Duarte, and M. A. S. Barrozo. "An Investigation of the Different Flow Regimes in a Rotating Drum through Experimental and Simulation." Materials Science Forum 802 (December 2014): 215–19. http://dx.doi.org/10.4028/www.scientific.net/msf.802.215.

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This paper aims to investigate the particle dynamic behavior in a rotating drum operating in a rolling regime under different rotating velocity, based on experimental results and simulations. Simple superphosphate fertilizer (SSP) was used as particulate matter in the current study. The Eulerian–Eulerian multiphase model along with the kinetic theory of granular flow was used in the simulations. In order to evaluate the simulation results, velocity distributions of the particulate phase were compared with experimental data. The experimental particle velocity distribution was obtained by using a high speed video camera. The numerical simulation results showed significant insights towards understanding of the particle dynamic in a rotating drum. The simulated results of particle velocity were in good agreement with the experimental data.
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24

Ahmed, Shofique Uddin, Rajesh Arora, and Om Parkash. "Flow Characteristics of Multiphase Glass Beads-Water Slurry through Horizontal Pipeline using Computational Fluid Dynamics." International Journal of Automotive and Mechanical Engineering 16, no. 2 (July 4, 2019): 6605–23. http://dx.doi.org/10.15282/ijame.16.2.2019.10.0497.

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Over the decades conveying solid particles through pipelines is a prevalent usage for many industries like food industries, pharmaceutical, oil and gas-solid handling, power generations etc. In the present study, slurry flow through 54.9 mm diameter and 4 m long horizontal pipe with solid particle diameter 0.125 mm and specific gravity 2.47 has been numerically analysed using a granular version of Eulerian two-phase model and RNG K- model. The solid particles are considered as mono-dispersed in the Eulerian model. These models are available in computational fluid dynamics (CFD) fluent software package. Non-uniform structured three-dimensional mesh with a refinement near wall boundary region has been selected for discretising the flow domain, and governing equations are solved using control volume finite difference method. Simulations are conducted at velocity varying from 1 m/s to 5 m/s and efflux concentration varying from 0.1 to 0.5 by volume. Different slurry flow parameters such as solid concentration distribution, velocity distribution, pressure drop etc. have been analysed from the simulated results. The simulated results of pressure drop are correlated with the experimental data available in previous literature and are found to be in excellent compliance with the experimental data.
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25

Ku, Kum-Song, Chol-Ho An, Kum-Chol Li, and Myong Il Kim. "An Eulerian model for the motion of granular material with a large Stokes number in fluid flow." International Journal of Multiphase Flow 92 (June 2017): 140–49. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2017.03.009.

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26

Gohel, Shitanshu, Shitalkumar Joshi, Mohammed Azhar, Marc Horner, and Gustavo Padron. "CFD Modeling of Solid Suspension in a Stirred Tank: Effect of Drag Models and Turbulent Dispersion on Cloud Height." International Journal of Chemical Engineering 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/956975.

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Many chemical engineering processes involve the suspension of solid particles in a liquid. In dense systems, agitation leads to the formation of a clear liquid layer above a solid cloud. Cloud height, defined as the location of the clear liquid interface, is a critical measure of process performance. In this study, solid-liquid mixing experiments were conducted and cloud height was measured as a function operating conditions and stirred tank configuration. Computational fluid dynamics simulations were then performed using an Eulerian-Granular multiphase model. The effects of hindered and unhindered drag models and turbulent dispersion force on cloud height were investigated. A comparison of the experimental and computational data showed excellent agreement over the full range of conditions tested.
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27

Gujjula, Ravi, and Narasimha Mangadoddy. "Prediction of Solid Recirculation Rate and Solid Volume Fraction in an Internally Circulating Fluidized Bed." International Journal of Computational Methods 12, no. 04 (August 2015): 1540005. http://dx.doi.org/10.1142/s0219876215400058.

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This paper presents a numerical study of gas and solid flow in an internally circulating fluidized bed (ICFB). Two-fluid Eulerian model with kinetic theory of granular flow option for solid phase stress closure and various drag laws were used to predict the hydrodynamic behavior of ICFB. 2D and 3D geometries were used to run the simulations. The 2D simulation results by various drag laws show that the Arastoopour and Gibilaro drag models able to predict the fluidization dynamics in terms of flow patterns, void fractions and axial velocity fields close to the experimental data. The effect of superficial gas velocity, presence of draft tube on solid hold-up distribution, solid circulation pattern, and variations in gas bypassing fraction for the 3D ICFB are investigated. The mechanism governing the solid circulation and solids concentration in an ICFB has been explained based on gas and solid dynamics obtained from the simulations. Predicted total granular temperature distributions in the draft tube and annular zones qualitatively agree with experimental data. The total granular temperature tends to increase with increasing solids concentration in the dilute region (ε < 0.1) and decreases with an increase of solids concentration in the dense region (ε > 0.1). In the dense zone, the decreasing trend in the granular temperature is mainly due to the reduction of the mean free path of the solid particles.
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28

Couto, Nuno, Valter Silva, Eliseu Monteiro, Paulo Brito, and Abel Rouboa. "Using an Eulerian-granular 2-D multiphase CFD model to simulate oxygen air enriched gasification of agroindustrial residues." Renewable Energy 77 (May 2015): 174–81. http://dx.doi.org/10.1016/j.renene.2014.11.089.

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29

Singh, G. K., B. Mohanty, P. Mondal, P. Chavan, and S. Datta. "Modeling and Simulation of a Pilot-Scale Bubbling Fluidized Bed Gasifier for the Gasification of High Ash Indian Coal Using Eulerian Granular Approach." International Journal of Chemical Reactor Engineering 14, no. 1 (February 1, 2016): 417–31. http://dx.doi.org/10.1515/ijcre-2014-0057.

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AbstractThe present work deals with modeling and simulation of a pilot-scale bubbling fluidized bed gasifier (BFBG) for the gasification of high ash Indian coal. Taking into account different stages of coal gasification, such as drying, volatilization, gasification and combustion processes, a two-dimensional model with quadrilateral cells is developed using FLUENT 12.0 software. The model incorporates exchange of mass, momentum and energy between gaseous phase (phase 1) and solid phase (phase 2) using Eulerian–Eulerian approach. The solid phase is described by kinetic theory of granular flows. Four heterogeneous and four homogeneous reactions covering six species in gaseous phase (CO, CO2, H2, N2, O2 and H2O) and coal in solid phase are considered for the above process. The kinetics for the homogeneous reactions are described using eddy dissipation model available in FLUENT while that for heterogeneous reactions, a user-defined function (UDF) with Arrhenius kinetics is written in C language. The validation of the above model has been done using experimental data generated in a pilot-scale BFBG at Center Institute of Mining and Fuel Research (CIMFR), Dhanbad, India. The computed exit gas compositions as well as temperature profile inside the gasifier are in good agreement (within an error band of ±10%) with experimental data. The flow behaviors and volume fraction profiles of gas and solid phases in the bed zone and freeboard zone of the gasifier have also been predicted using this model.
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30

Nemoda, Stevan, Milica Mladenovic, Milijana Paprika, Aleksandar Eric, and Borislav Grubor. "Three phase Eulerian-granular model applied on numerical simulation of non-conventional liquid fuels combustion in a bubbling fluidized bed." Thermal Science 20, suppl. 1 (2016): 133–49. http://dx.doi.org/10.2298/tsci151025196n.

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The paper presents a two-dimensional CFD model of liquid fuel combustion in bubbling fluidized bed. The numerical procedure is based on the two-fluid Euler-Euler approach, where the velocity field of the gas and particles are modeled in analogy to the kinetic gas theory. The model is taking into account also the third - liquid phase, as well as its interaction with the solid and gas phase. The proposed numerical model comprise energy equations for all three phases, as well as the transport equations of chemical components with source terms originated from the component conversion. In the frame of the proposed model, user sub-models were developed for heterogenic fluidized bed combustion of liquid fuels, with or without water. The results of the calculation were compared with experiments on a pilot-facility (power up to 100 kW), combusting, among other fuels, oil. The temperature profiles along the combustion chamber were compared for the two basic cases: combustion with or without water. On the basis of numerical experiments, influence of the fluid-dynamic characteristics of the fluidized bed on the combustion efficiency was analyzed, as well as the influence of the fuel characteristics (reactivity, water content) on the intensive combustion zone.
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31

Wang, Min, Yingya Wu, Xiaogang Shi, Xingying Lan, Chengxiu Wang, and Jinsen Gao. "Comparison of Riser-Simplified, Riser-Only, and Full-Loop Simulations for a Circulating Fluidized Bed." Processes 7, no. 5 (May 22, 2019): 306. http://dx.doi.org/10.3390/pr7050306.

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With the development of computing power, the simulation of circulating fluidized bed (CFB) has developed from riser-simplified simulation to riser-only simulation, then to full-loop simulation. This paper compared these three methods based on pilot-scale CFB experiment data to find the scope of application of each method. All these simulations, using the Eulerian–Eulerian two-fluid model with the kinetic theory of granular theory, were conducted to simulate a pilot-scale CFB. The hydrodynamics, such as pressure balance, solids holdup distribution, solids velocity distribution, and instantaneous mass flow rates in the riser or CFB system, were investigated in different simulations. By comparing the results from different methods, it was found that riser-simplified simulation is not sufficient to obtain accurate hydrodynamics, especially in higher solids circulating rates. The riser-only simulation is able to make a reasonable prediction of time-averaged behaviors of gas–solids in most parts of riser but the entrance region. Further, the full-loop simulation can not only predict precise results, but also obtain comprehensive details and instantaneous information in the CFB system.
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32

Mousa, Moataz Bellah M., Seif-Eddeen K. Fateen, and Essam A. Ibrahim. "Hydrodynamics of a Novel Design Circulating Fluidized Bed Steam Reformer Operating in the Dense Suspension Upflow Regime." ISRN Chemical Engineering 2014 (February 10, 2014): 1–13. http://dx.doi.org/10.1155/2014/935750.

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Circulating fluidized bed steam reformers (CFBSR) represent an important alternative for hydrogen production, a promising energy carrier. Although the reactor hydrodynamics play crucial role, modeling efforts to date are limited to one-dimensional models, thus ignoring many of the flow characteristics of fluidized beds that have strong effects on the reactor efficiency. The flow inside the riser is inherently complex and requires at least two-dimensional modeling to capture its details. In the present work, the computational fluid dynamics (CFD) simulations of the hydrodynamics of the riser part of a novel CFBSR were carried out using two-phase Eulerian-Eulerian approach coupled with kinetic theory of granular flow and K-ε model. Cold flow simulations were carried under different fluidization regimes. It was found that catalyst of Geldart's type “A” particle is more efficient for flow inside the catalytic reactor and dense suspension upflow (DSU) fluidization regime yields the best homogeneous catalyst distribution in the riser and thus best reactor performance. The optimum range for catalyst flux was found to be higher than 1150 kg/m2·s for a gas flux of 6.78 kg/m2·s. It was also noted that the value of 500 Kg/m2·s for catalyst flux represents the critical value below which the riser will operate under pneumatic transport regime.
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33

Wei, Liping, Yukuan Gu, Yibin Wang, and Youjun Lu. "Multi-fluid Eulerian simulation of fluidization characteristics of mildly-cohesive particles: Cohesive parameter determination and granular flow kinetic model evaluation." Powder Technology 364 (March 2020): 264–75. http://dx.doi.org/10.1016/j.powtec.2020.01.081.

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34

Chen, Jia, and Wende Xiao. "Solids Suspension Study in a Side-Entering Stirred Tank Through CFD Modeling." International Journal of Chemical Reactor Engineering 11, no. 1 (July 4, 2013): 331–46. http://dx.doi.org/10.1515/ijcre-2012-0062.

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Abstract Computational fluid dynamics (CFD) technique was employed to study solids suspension in a stirred tank equipped with three side-entering impellers. Simulations of solid–liquid flow were performed by using an Eulerian-Granular Multiphase (EGM) model coupling with standard k–ε mixture turbulence model and Reynolds stress model, respectively. A multiple reference frame (MRF) approach was used to model the impeller rotation. The CFD predictions have been verified by comparing the predicted results with the experimental just suspended impeller speed and solid sediment pattern at the tank bottom. The solid distribution and liquid-phase velocity vectors throughout the tank for two cases with and without solid phase were investigated to understand the characteristics of solid–liquid flow. The solid suspension quality has been assessed by employing three criterions: the just suspended impeller speed Njs, cloud height h, and suspension homogeneity. The effects of impeller agitation speed, particle size, and solid loading on suspension quality have been investigated. The computational model and results discussed in this study would be useful to understand the solid–liquid dispersion process in side-entering stirred tanks and extend the application of CFD models for equipment design and process optimization.
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35

Md Isa, Kamariah, Kahar Osman, Nik Rosli Abdullah, Azfarizal Mukhtar, and Nor Fadzilah Othman. "CFD Modelling of a Fluidized Bed Gasifier; Effects of Drag Model and Bed Heights." Applied Mechanics and Materials 699 (November 2014): 730–35. http://dx.doi.org/10.4028/www.scientific.net/amm.699.730.

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One of the unresolved issues in using the gasifier is the inability to determine the occurrence of the transition regime of fluidized bed. In modeling gas-solid phase, drag force is one of the main mechanisms for inter-phase momentum transfer. Thus, a simulation of fluidized bed was developed to study the effect of using various drag models over different bed height of H/D ratio such as 0.5, 1 and 2. A two dimensional model using Eulerian-Granular Multiphase Model (EGM) based on two fluid models have been used to simulate hydrodynamics of a bubbling fluidized beds. Gas-solid interactions are modeled via inter-phase of a drag model. The drag correlations of Gidaspow, Wen Yu, Syamlal-O'Brien, Hill Koch Ladd (HKL) and Representative Unit Cell (RUC) were implemented to simulate the interaction between phases. From this study, we found that different H/D ratio such as 0.5, 1 and 2 yields different volume fraction as increasing bed height slows kinetic transport of particle sand to the upper side of the bed. Besides that, different H/D ratio also resulted in different velocity vector. The results also show that Wen Yu and Syamlal-O'Brien are sufficient enough in detecting the change from one regime to another regardless of the bed height.
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36

Kumar Gopaliya, Manoj, and D. R. Kaushal. "Modeling of sand-water slurry flow through horizontal pipe using CFD." Journal of Hydrology and Hydromechanics 64, no. 3 (September 1, 2016): 261–72. http://dx.doi.org/10.1515/johh-2016-0027.

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Abstract The paper presents three-dimensional CFD analysis of two-phase (sand-water) slurry flows through 263 mm diameter pipe in horizontal orientation for mixture velocity range of 3.5-4.7 m/s and efflux concentration range of 9.95-34% with three particle sizes viz. 0.165 mm, 0.29 mm and 0.55 mm with density 2650 kg/m3. RNG k-ε turbulence closure equations with Eulerian multi-phase model is used to simulate various slurry flows. The simulated values of local solid concentration are compared with the experimental data and are found to be in good agreement for all particle sizes. Effects of particle size on various slurry flow parameters such as pressure drop, solid phase velocity distribution, friction factor, granular pressure, turbulent viscosity, turbulent kinetic energy and its dissipation have been analyzed.
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37

Paula, Jéssica Aparecida Apolinário de, Érica Victor de Faria, Ana Christina Pitard Lima, José Luiz Vieira Neto, and Kássia Graciele dos Santos. "Computational simulation of soybean particles flow in a hopper using computational fluid dynamics (CFD) and discrete elements method (DEM)." Research, Society and Development 9, no. 8 (July 13, 2020): e448985463. http://dx.doi.org/10.33448/rsd-v9i8.5463.

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The hoppers are the most common structures used in storage units for agricultural products such as grains and cereals. The soybean, which is one of the most common products in Brazil spend most of their time in a hopper between the stages of picking and shipment. Problems such as damage to the hopper structures during the outflow are factors that have been the subject of studies using computational models. Computational Fluid Dynamics (CFD) has played a big role in gas-solid systems study, together with the Discrete Element Method (DEM). This method manages both fluid phase as the solid phase, which in this case is granular, through the Eulerian and Lagrangian approach. The DEM is based on the interaction between the particles and each one is separately monitored. This work aims to calibrate the parameters of the spring-dashpot model, in the granular dynamics of fluids study, which influences the contact between the soy particles in the silo. For this purpose, a comparison was made of the experimental discharge time of soybeans into a hopper, with the time resulting from 27 simulations generated by a central composite design (CCD). Through the analysis of the simulations and statistics, it was possible to identify the factors that influence whether or not the time of discharge and establish a calibration of these parameters that best describe the experimental results.
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38

Qu, Jingyu, Tie Yan, Xiaofeng Sun, Zijian Li, and Wei Li. "Decaying Swirl Flow and Particle Behavior through the Hole Cleaning Device for Horizontal Drilling of Fossil Fuel." Energies 12, no. 3 (January 22, 2019): 336. http://dx.doi.org/10.3390/en12030336.

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The hole cleaning device is a powerful application which can effectively slow down the deposition of cuttings during drilling. However, in this complicated swirl flow created by the device, the decay of the swirl flow and the particle behavior are not evident yet. In this paper, the decay of the swirl flow and the particle behavior in the swirl flow field are studied by the Eulerian–Eulerian two-fluid model (TFM) coupled with the kinetic theory of granular flows (KTGF), and sliding mesh (SM) technique for simulating the fluid flow. The results show that the swirl intensity decays exponentially along the flow direction under laminar flow conditions. The swirl flow has a longer acting distance at a higher rotational speed, which can effectively slow down the deposition of cutting particles. The initial swirl intensity of swirl flow induced by the blades increases significantly with the increase of blade height and the decrease of the blade angle. The tangential velocity of the cutting particles in the annulus is more significant near the central region, gradually decreases toward the wall in the radial direction, and rapidly decreases to 0 at the wall surface. The decay rate is negatively correlated with the initial swirl intensity. The results presented here may provide a useful reference for the design of the hole cleaning device.
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39

Innocenti, A., R. O. Fox, M. V. Salvetti, and S. Chibbaro. "A Lagrangian probability-density-function model for collisional turbulent fluid–particle flows." Journal of Fluid Mechanics 862 (January 11, 2019): 449–89. http://dx.doi.org/10.1017/jfm.2018.895.

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Inertial particles in turbulent flows are characterised by preferential concentration and segregation and, at sufficient mass loading, dense particle clusters may spontaneously arise due to momentum coupling between the phases. These clusters, in turn, can generate and sustain turbulence in the fluid phase, which we refer to as cluster-induced turbulence (CIT). In the present work, we tackle the problem of developing a framework for the stochastic modelling of moderately dense particle-laden flows, based on a Lagrangian probability-density-function formalism. This framework includes the Eulerian approach, and hence can be useful also for the development of two-fluid models. A rigorous formalism and a general model have been put forward focusing, in particular, on the two ingredients that are key in moderately dense flows, namely, two-way coupling in the carrier phase, and the decomposition of the particle-phase velocity into its spatially correlated and uncorrelated components. Specifically, this last contribution allows us to identify in the stochastic model the contributions due to the correlated fluctuating energy and to the granular temperature of the particle phase, which determine the time scale for particle–particle collisions. The model is then validated and assessed against direct-numerical-simulation data for homogeneous configurations of increasing difficulty: (i) homogeneous isotropic turbulence, (ii) decaying and shear turbulence and (iii) CIT.
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40

Long, Xin Feng, Yi Liu, and Bo Lou. "Simulation of Gas-Solid Flow Characteristics in Three-Dimensional Rotational Spouted-Fluidized Bed." Applied Mechanics and Materials 496-500 (January 2014): 913–17. http://dx.doi.org/10.4028/www.scientific.net/amm.496-500.913.

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In order to study the gas-solid flow characteristics in a rotational spouted-fluidized bed dryer, the eulerian multi-phase model was applied in three-dimensional numerical simulation of a rotational spouted-fluidized bed to analyze the effect of different velocity ratios between bottom and tangential wind on gas and particle velocity distribution characteristics, and the change rule of gas-solid flow state with the time at the velocity ratio of 30 m·s-1/30 m·s-1 was derived. The results show that the increase of tangential wind velocity is propitious to enhance the gas flow rate in the region near the wall and make the gas-solid phase mix sufficiently as well as augment of the contact area of gas and particle phase, and decrease of the gas flow dead zones and the adhesion of viscous materials to cylinder wall. However, the negative pressure formed by the entrainment effect of tangential wind goes against the development of gas flow along the axial direction reducing the penetration effect of axial wind to the granular layer.
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41

Pezo, Lato, Milada Pezo, Aca Jovanovic, Nenad Kosanic, Aleksandar Petrovic, and Ljubinko Levic. "Granular flow in static mixers by coupled DEM/CFD approach." Chemical Industry 70, no. 5 (2016): 539–46. http://dx.doi.org/10.2298/hemind151013060p.

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The mixing process greatly influence the mixing efficiency, as well as the quality and the price of the intermediate and/or the final product. Static mixer is used for premixing action before the main mixing process, for significant reduction of mixing time and energy consumption. This type of premixing action is not investigated in detail in the open literature. In this article, the novel numerical approach called Discrete Element Method is used for modelling of granular flow in multiple static mixer applications (1 - 3 Komax or Ross mixing elements were utilized), while the Computational Fluid Dynamic method was chosen for fluid flow modelling, using the Eulerian multiphase model. The main aim of this article is to predict the behaviour of granules being gravitationally transported in different mixer configuration and to choose the best configuration of the mixer taking into account the total particle path, the number of mixing elements and the quality of the obtained mixture. The results of the numerical simulations in the static mixers were compared to experimental results, the mixing quality is examined by RSD (relative standard deviation) criterion, and the effects on the mixer type and the number of mixing elements on mixing process were studied. The effects of the mixer type and the number of mixing elements on mixing process were studied using analysis of variance (ANOVA). Mathematical modelling is used for optimization of number of Ross and Komax segments in mixer in order to gain desirable mixing results.
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42

Cai, Gaoshen, Jubo Fu, Chuanyu Wu, Kangning Liu, and Lihui Lang. "Simulation and Experimental Investigation of Granular Medium Forming Technology on Titanium Alloy Sheet at 500 °C." Metals 11, no. 1 (January 8, 2021): 114. http://dx.doi.org/10.3390/met11010114.

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To investigate and verify the degree to which the forming properties of low plasticity materials are improved at room temperature using the granular medium forming (GMF) process at 500 °C, a coupled Eulerian–Lagrangian unit calculation model was established and a special mold was designed to conduct a GMF experiment for titanium alloy sheets under different-shaped pressing blocks. Then, using a three-coordinate measuring machine, the sizes of the outer contours of the parts formed at room temperature were measured, and the results showed that the bottom of the parts maintained a smooth surface during the drawing process. As the drawing height increased, the radius of curvature of the cambered surface gradually decreased. By measuring the wall thickness of the parts at different positions from the central axis using a caliper, the wall thickness distribution curves of these parts were obtained, which showed that the deformations of the bottom of the formed parts were uniform and the uniformity of the wall thickness distribution was good. By comparing the GMF experimental data at 500 °C with traditional deep drawing experimental data, it was found that the GMF technology could improve the forming properties of low plastic materials such as titanium alloys.
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43

Cai, Gaoshen, Jubo Fu, Chuanyu Wu, Kangning Liu, and Lihui Lang. "Simulation and Experimental Investigation of Granular Medium Forming Technology on Titanium Alloy Sheet at 500 °C." Metals 11, no. 1 (January 8, 2021): 114. http://dx.doi.org/10.3390/met11010114.

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To investigate and verify the degree to which the forming properties of low plasticity materials are improved at room temperature using the granular medium forming (GMF) process at 500 °C, a coupled Eulerian–Lagrangian unit calculation model was established and a special mold was designed to conduct a GMF experiment for titanium alloy sheets under different-shaped pressing blocks. Then, using a three-coordinate measuring machine, the sizes of the outer contours of the parts formed at room temperature were measured, and the results showed that the bottom of the parts maintained a smooth surface during the drawing process. As the drawing height increased, the radius of curvature of the cambered surface gradually decreased. By measuring the wall thickness of the parts at different positions from the central axis using a caliper, the wall thickness distribution curves of these parts were obtained, which showed that the deformations of the bottom of the formed parts were uniform and the uniformity of the wall thickness distribution was good. By comparing the GMF experimental data at 500 °C with traditional deep drawing experimental data, it was found that the GMF technology could improve the forming properties of low plastic materials such as titanium alloys.
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44

Capecelatro, Jesse, Olivier Desjardins, and Rodney O. Fox. "On fluid–particle dynamics in fully developed cluster-induced turbulence." Journal of Fluid Mechanics 780 (September 7, 2015): 578–635. http://dx.doi.org/10.1017/jfm.2015.459.

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At sufficient mass loading and in the presence of a mean body force (e.g. gravity), an initially random distribution of particles may organize into dense clusters as a result of momentum coupling with the carrier phase. In statistically stationary flows, fluctuations in particle concentration can generate and sustain fluid-phase turbulence, which we refer to as cluster-induced turbulence (CIT). This work aims to explore such flows in order to better understand the fundamental modelling aspects related to multiphase turbulence, including the mechanisms responsible for generating volume-fraction fluctuations, how energy is transferred between the phases, and how the cluster size distribution scales with various flow parameters. To this end, a complete description of the two-phase flow is presented in terms of the exact Reynolds-average (RA) equations, and the relevant unclosed terms that are retained in the context of homogeneous gravity-driven flows are investigated numerically. An Eulerian–Lagrangian computational strategy is used to simulate fully developed CIT for a range of Reynolds numbers, where the production of fluid-phase kinetic energy results entirely from momentum coupling with finite-size inertial particles. The adaptive filtering technique recently introduced in our previous work (Capecelatro et al., J. Fluid Mech., vol. 747, 2014, R2) is used to evaluate the Lagrangian data as Eulerian fields that are consistent with the terms appearing in the RA equations. Results from gravity-driven CIT show that momentum coupling between the two phases leads to significant differences from the behaviour observed in very dilute systems with one-way coupling. In particular, entrainment of the fluid phase by clusters results in an increased mean particle velocity that generates a drag production term for fluid-phase turbulent kinetic energy that is highly anisotropic. Moreover, owing to the compressibility of the particle phase, the uncorrelated components of the particle-phase velocity statistics are highly non-Gaussian, as opposed to systems with one-way coupling, where, in the homogeneous limit, all of the velocity statistics are nearly Gaussian. We also observe that the particle pressure tensor is highly anisotropic, and thus additional transport equations for the separate contributions to the pressure tensor (as opposed to a single transport equation for the granular temperature) are necessary in formulating a predictive multiphase turbulence model.
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45

Thankachan, Issac, S. Rupesh, and C. Muraleedharan. "CFD Modelling of Biomass Gasification in Fluidized-Bed Reactor Using the Eulerian-Eulerian Approach." Applied Mechanics and Materials 592-594 (July 2014): 1903–8. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.1903.

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A comprehensive two dimensional numerical model has been developed to simulate the biomass gasification in a fluidised bed reactor. Gas-solid flows as well as the chemical reactions are considered. Euler-Euler model is adopted to describe the multiphase flow regime inside the reactor. The standard k-є model is used to model the turbulence for each phase. The particle motion inside the reactor is modelled using various drag laws derived from Kinetic Theory of Granular Flow. Biomass fuel after pyrolysis is fed as char and volatile matter. The reaction rates of homogeneous reactions and heterogeneous reactions are determined by Eddy dissipation reaction rate and Arrhenius-Diffusion reaction rate, respectively. Gas velocities, flow patterns, composition of gas product and distribution of reaction rates are obtained. Results are compared with experimental data and found to be in agreement.
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46

Gu, Yile, Ali Ozel, Jari Kolehmainen, and Sankaran Sundaresan. "Computationally generated constitutive models for particle phase rheology in gas-fluidized suspensions." Journal of Fluid Mechanics 860 (December 4, 2018): 318–49. http://dx.doi.org/10.1017/jfm.2018.856.

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Developing constitutive models for particle phase rheology in gas-fluidized suspensions through rigorous statistical mechanical methods is very difficult when complex inter-particle forces are present. In the present study, we pursue a computational approach based on results obtained through Eulerian–Lagrangian simulations of the fluidized state. Simulations were performed in a periodic domain for non-cohesive and mildly cohesive (Geldart Group A) particles. Based on the simulation results, we propose modified closures for pressure, bulk viscosity, shear viscosity and the rate of dissipation of pseudo-thermal energy. For non-cohesive particles, results in the high granular temperature $T$ regime agree well with constitutive expressions afforded by the kinetic theory of granular materials, demonstrating the validity of the methodology. The simulations reveal a low $T$ regime, where the inter-particle collision time is determined by gravitational fall between collisions. Inter-particle cohesion has little effect in the high $T$ regime, but changes the behaviour appreciably in the low $T$ regime. At a given $T$, a cohesive particle system manifests a lower pressure at low particle volume fractions when compared to non-cohesive systems; at higher volume fractions, the cohesive assemblies attain higher coordination numbers than the non-cohesive systems, and experience greater pressures. Cohesive systems exhibit yield stress, which is weakened by particle agitation, as characterized by $T$. All these effects are captured through simple modifications to the kinetic theory of granular materials for non-cohesive materials.
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47

Ejtehadi, Omid, and R. S. Myong. "A modal discontinuous Galerkin method for simulating dusty and granular gas flows in thermal non-equilibrium in the Eulerian framework." Journal of Computational Physics 411 (June 2020): 109410. http://dx.doi.org/10.1016/j.jcp.2020.109410.

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48

Lettieri, Paola, Luca Cammarata, Giorgio D. M. Micale, and John Yates. "CFD Simulations of Gas Fluidized Beds Using Alternative Eulerian-Eulerian Modelling Approaches." International Journal of Chemical Reactor Engineering 1, no. 1 (November 20, 2002). http://dx.doi.org/10.2202/1542-6580.1007.

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A commercially available Computational Fluid-Dynamics code, CFX-4, has been chosen to carry out computer simulations of gas fluidized beds. In this study, the Eulerian-Eulerian granular kinetic model, which is a standard option of the code, has been used. Fluid-bed simulations of Geldart Group B materials have been performed using the granular kinetic model, spanning three hydrodynamic regimes: bubbling, slugging and turbulent fluidization. Furthermore, an alternative Eulerian-Eulerian model, the so-called "particle-bed model", has been implemented for the first time within a commercial code, and results are presented from simulations of the bubbling and slugging fluidization of a Geldart Group B material, and for the homogeneous fluidization of a Group A material. A numerical procedure has been developed to allow for a tight control of the fluid-bed voidage at maximum packing during the simulations with the particle-bed model. Results show that both the granular kinetic model approach and the particle-bed model are able to describe significant aspects of the investigated fluidization regimes.
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Cammarata, Luca, Paola Lettieri, Giorgio D. M. Micale, and Derek Colman. "2D and 3D CFD Simulations of Bubbling Fluidized Beds Using Eulerian-Eulerian Models." International Journal of Chemical Reactor Engineering 1, no. 1 (October 28, 2003). http://dx.doi.org/10.2202/1542-6580.1083.

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This paper reports on CFD simulations of freely bubbling gas fluidized beds using CFX-4, a commercial code developed by CFX Ltd. (formerly AEA Technology). Two Eulerian-Eulerian modelling approaches, the granular kinetic model and the particle-bed model (Gibilaro, 2001), have been investigated. The particle bed model has been recently implemented in CFX-4 for 2D simulations and a numerical procedure was developed to allow for a tight control of the fluid-bed voidage at maximum packing during the simulations, see Lettieri et al. (2003). The work has now been extended to 3D simulations and qualitative and quantitative results are presented in this paper for both the 2D and 3D simulations of the bubbling fluidization of a Geldart Group B material. Results on bed expansion, bubble size and bubble hold-up are reported. In particular, simulated bubble size is compared with predictions given by the Darton et al. (1977) equation at different bed heights. The paper shows that the bubble size predicted by both the granular kinetic model and the particle-bed model is in good agreement with the Darton's equation.
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50

Uz Zaman, Ashraf, and Donald John Bergstrom. "Implementation of Two-Fluid Model for Dilute Gas-Solid Flow in Pipes With Rough Walls." Journal of Fluids Engineering 136, no. 3 (January 16, 2014). http://dx.doi.org/10.1115/1.4026282.

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A numerical study was carried out to investigate the performance of a two-layer model for predicting turbulent gas-particle flows in rough pipes. An Eulerian–Eulerian two-fluid formulation was used to model both the gas and solid phases for turbulent gas-particle flow in a vertical tube. The stresses developed in the particle phase were calculated using the kinetic theory of granular flows while the gas-phase stresses were described using an eddy viscosity model. The two-fluid model typically uses a two-equation k-ɛ model to describe the gas phase turbulence, which includes the suppression and enhancement effects due to the presence of particles. For comparison, a two-layer model was also implemented since it has the capability to include surface roughness. The current study examines the predictions of the two-layer model for both clear gas and gas-solid flows in comparison to the results of a conventional low Reynolds number model. The paper specifically documents the effects of surface roughness on the turbulence kinetic energy and granular temperature for gas-particle flow in both smooth and rough pipes.
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