Academic literature on the topic 'Multi-Phase granular flow'
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Journal articles on the topic "Multi-Phase granular flow":
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Djebbar, R., S. B. Beale, and M. Sayed. "Numerical Study of Two-Phase Granular Flow for Process Equipment." Journal of Pressure Vessel Technology 122, no. 4 (February 1, 2000): 462–68. http://dx.doi.org/10.1115/1.1310366.
Abstract:
This paper reports on a research program of modeling multi-phase granular flow. Both single-phase granular flow and two-phase liquid/granular flow in a pressure vessel were considered. For the latter case, detailed results based on a viscous/Mohr-Coulomb closure were compared to existing formulations. Idealized test cases indicated that the numerical procedure is sound. Subsequent simulations of two-phase flow using realistic geometries and boundary conditions showed that the pressure distribution in the solid phase is fundamentally different for the Mohr-Coulomb system than for the conventional system. The effect of the angle of internal friction, geometry, and other parameters is discussed. [S0094-9930(00)01204-X]
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Elmisaoui, Safae, Saad Benjelloun, Radouan Boukharfane, Lhachmi Khamar, Sanae Elmisaoui, and Mohamed Khamar. "In Silico CFD Investigation of the Granulation Hydrodynamics in Rotating Drum: Process Sensitivity to the Operating Parameters and Drag Models." Processes 10, no. 10 (September 26, 2022): 1939. http://dx.doi.org/10.3390/pr10101939.
Abstract:
Computational fluid dynamics (CFD) have been extensively used to simulate the hydrodynamics of multiphase flows (MPFs) in rotating machinery. In the presence of a granular dense phase, the Kinetic Theory of Granular Flow (KTGF) is usually coupled to Eulerian multi-fluid models to obtain tractable computational fluid models. In the present work, the hydrodynamic behavior of a three dimensional, industrial scale, and rotating drum granulator with gas–solid flows is assessed using the Eulerian–Eulerian approach coupled with the k-ε standard turbulence model. A Eulerian–Eulerian Two-Fluid Model (TFM) is used with the KTGF model for the granular phase. The sensitivities to different operating parameters, including the rotational speed (8, 16, and 24 rpm), inclination degree (3.57∘, 5.57∘, and 7.57∘), and degree of filling (20%, 30%, and 40%) are studied. Moreover, the impact of the drag model on the simulation accuracy is investigated. The flow behavior, regime transitions, and particle distribution are numerically evaluated, while varying the operating conditions and the drag models. The rotational speed and filling degree appear to have greater influences on the granulation effectiveness than on the inclination degree. Three drag models are retained in our analysis. Both the Gidaspow and Wen and Yu models successfully predict the two-phase flow in comparison to the Syamlal and O’Brien model, which seems to underestimate the hydrodynamics of the flow in both its axial and radial distributions (a fill level less than 35%). The methodology followed in the current work lays the first stone for the optimization of the phosphates fertilizer wet-granulation process within an industrial installation.
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VARSAKELIS, C., and M. V. PAPALEXANDRIS. "Low-Mach-number asymptotics for two-phase flows of granular materials." Journal of Fluid Mechanics 669 (January 12, 2011): 472–97. http://dx.doi.org/10.1017/s0022112010005173.
Abstract:
In this paper, we generalize the concept of low-Mach-number approximation to multi-phase flows and apply it to the two-phase flow model of Papalexandris (J. Fluid Mech., vol. 517, 2004, p. 103) for granular materials. In our approach, the governing system of equations is first non-dimensionalized with values that correspond to a reference thermodynamic state of the phase with the smaller speed of sound. By doing so, the Mach number based on this reference state emerges as a perturbation parameter of the equations in hand. Subsequently, we expand each variable in power series of this parameter and apply singular perturbation techniques to derive the low-Mach-number equations. As expected, the resulting equations are considerably simpler than the unperturbed compressible equations. Our methodology is quite general and can be directly applied for the systematic reduction of continuum models for granular materials and for many different types of multi-phase flows. The structure of the low-Mach-number equations for two special cases of particular interest, namely, constant-density flows and the equilibrium limit is also discussed and analysed. The paper concludes with some proposals for experimental validation of the equations.
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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.
Abstract:
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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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.
Abstract:
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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Rahaman, Fardausur, Abd Alhamid Rafea Sarhan, and Jamal Naser. "Numerical Analysis of Multi-Particulate Flow Behaviour in CFB Riser Coupled with a Kinetic Theory." Fluids 8, no. 9 (September 21, 2023): 257. http://dx.doi.org/10.3390/fluids8090257.
Abstract:
In this work, a three-dimensional CFD model for the gas–solid flow of two different particle sizes in a CFB riser coupled with a kinetic theory (KT) has been developed. The properties of the solid phases are calculated using the proposed multi-particle kinetic theory. The CFD model is implemented in the commercial CFD software CFX4.4. In the current model, one gas phase and two solid phases are used. However, the model is generalised for one carrier phase and N number of solid phases to enable a realistic particle size distribution in the system. The momentum, volume fraction and granular temperature equations are solved for each individual solid phase and implemented into the CFD model through user-defined functions (UDFs). The k-ε turbulence model is used in simulating the circulating fluidised bed model. For verification, simulation results obtained with the new KT model were compared with experimental data, and then the model was used for further analysis. It was found that the proposed multi-particle model can be used to calculate the properties of gas–solid systems with particles of different sizes and/or densities, removing the assumptions of previous models that required all the particles to be of an equal mass, size and density.
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Huang, Jun, Guang Yin, Muk Chen Ong, Dag Myrhaug, and Xu Jia. "Numerical Investigation of Scour Beneath Pipelines Subjected to an Oscillatory Flow Condition." Journal of Marine Science and Engineering 9, no. 10 (October 9, 2021): 1102. http://dx.doi.org/10.3390/jmse9101102.
Abstract:
The present study carries out two-dimensional numerical simulations to investigate scour beneath a single pipeline and piggyback pipelines subjected to an oscillatory flow condition at a Keulegan–Carpenter (KC) number of 11 using SedFoam (an open-source, multi-dimensional Eulerian two-phase solver for sediment transport based on OpenFOAM). The turbulence flow is resolved using the two-phase modified k−ω 2006 model. The particle stresses due to the binary collisions and enduring contacts among the sediments are modeled using the rheology model of granular flow. The present numerical model is validated for the scour beneath a single pipeline, and the simulated sediment profiles are compared with published experimental data and numerical simulation results. The scour process beneath three different piggyback pipelines under the same flow condition are also considered, and the scour development and surrounding flow patterns are discussed in detail. Typical steady-streaming structures around the pipeline due to the oscillatory flow condition are captured. The scour depth during the initial development of the scour process for the piggyback pipeline with the small pipeline placed above the large one is the largest among all the investigated configurations. The phase-averaged flow fields show that the flow patterns are influenced by the additional small pipeline.
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Lee, Cheng-Hsien, and Zhenhua Huang. "Effects of grain size on subaerial granular landslides and resulting impulse waves: experiment and multi-phase flow simulation." Landslides 19, no. 1 (October 1, 2021): 137–53. http://dx.doi.org/10.1007/s10346-021-01760-z.
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Xing, Xuelian, Chao Zhang, Bin Jiang, Yongli Sun, Luhong Zhang, and Cedric Briens. "Effect of a Baffle on Bubble Distribution in a Bubbling Fluidized Bed." Processes 9, no. 7 (June 30, 2021): 1150. http://dx.doi.org/10.3390/pr9071150.
Abstract:
In this study, the multi-phase Eulerian–Eulerian two-fluid method (TFM) coupled with the kinetic theory of granular flow (KTGF) was used to investigate the hydrodynamics of particle flows (Geldart Group B) in a lab-scale bubbling fluidized bed. The goal was to improve the bubble flow behavior inside the fluidized bed to improve the distribution of an injected liquid, by increasing the flow of bubbles entering the spray jet cavity and, thus, reduce the formation of wet agglomerates. The effects of a baffle on both the injection level and the whole fluidized bed were studied. Different baffle geometries were also investigated. Adding a fluxtube to a baffle can improve the bubble flows and a long fluxtube works best at redirecting gas bubbles. Baffles tend to smooth out variations in the gas distribution caused by the non-uniform inlet gas distribution. A gas pocket appears under all the baffles.
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Benavides-Morán, Aldo Germán, and Santiago Lain. "Improving Solid-Phase Fluidization Prediction in Circulating Fluidized Bed Risers: Drag Model Sensitivity and Turbulence Modeling." Mathematics 12, no. 12 (June 14, 2024): 1852. http://dx.doi.org/10.3390/math12121852.
Abstract:
This contribution underscores the importance of selecting an appropriate interphase momentum transfer model for accurately predicting the distribution of the solid phase in a full-scale circulating fluidized bed (CFB) riser equipped with a smooth C-type exit. It also explores other critical factors such as domain configuration, grid size, the scope of time averaging, and turbulence modulation. The flow in a cold-CFB riser is simulated using the Eulerian–Eulerian two-fluid model within a commercial CFD package. Particle interactions in the rapid-flow regime are determined utilizing the kinetic theory of granular flow while enduring particle contacts are accounted for by incorporating frictional stresses. The turbulent dynamics of the continuous phase are described using two-equation turbulence models with additional modulation terms. The three-dimensional computational domain replicates an actual CFB riser geometry where experimental measurements are available for particulate phase axial and radial solid concentration. The simulation results reveal that the choice of drag model correlation significantly impacts both axial and radial solid distribution. Notably, the energy-minimization multi-scale drag model accurately depicts the dense solid region at the bottom and core–annular flow structure in the upper part. The solid-phase fluidization is overestimated in the lower riser section when a 2D domain is utilized. Neglecting turbulence modulation terms in the k-ω SST model results in nearly flat solid volume fraction radial profiles in the analyzed upper sections of the riser, resembling those obtained with the k-ϵ model.
Dissertations / Theses on the topic "Multi-Phase granular flow":
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Hamidi, Mohamed Salim. "Direct numerical simulations of flow in dense fluid-particle systems." Electronic Thesis or Diss., Perpignan, 2024. http://www.theses.fr/2024PERP0004.
Abstract:
Les écoulements de fluide particules jouent un rôle important dans une variété d’applications industrielles, particulièrement dans le contexte des centrales solaires à concentration de troisième génération, où ils peuvent être utilisés à la fois comme fluide caloporteur et moyen de stockage thermique. Cependant, l’étude de ces écoulements présente des défis considérables en raison de la complexité des interactions multi-échelles qui les régissent. La simulation numérique, et en particulier les méthodes de Simulation Numérique Directe (DNS) où la résolution est inférieure au diamètre des particules, émerge comme un outil prometteur pour mieux comprendre ces écoulements. L’augmentation des moyens de calcul et la performance des algorithmes numériques ont rendu les simulations de lits fluidisés avec particules résolues de plus en plus réalisablespour des études à des échelles représentatives. Dans cette thèse, nous présentons une méthode numérique basée sur la formulation mono-fluide. Cette méthode combine la méthode de suivi de front avec la méthode de pénalisation visqueuse pour simuler les comportements des écoulements particulaires. La méthode de suivi de front utilise un système de maillage double. Ce système suit efficacement les interfaces solides en mouvement, représentées par un maillage mobile, à travers une grille de simulation fixe, garantissant ainsi la précision dans la représentation des mouvements des particules. La méthode de pénalisation visqueuse, quant à elle, joue un rôle essentiel pour assurer la condition de non-déformation à l’intérieur des particules. Cela est réalisé en traitant le fluide à l’intérieur des particules comme un milieu extrêmement visqueux, permettantainsi à la simulation de reproduire de manière réaliste le comportement des particules solides dans diverses conditions. Pour les interactions à courte distance entre les particules, un modèle de collision combiné est utilisé. Ce modèle prend habilementen compte à la fois la dissipation visqueuse et la dissipation solide, principalement dues aux effets de lubrification et aux contacts inélastiques entre les particules, respectivement. L’approche nuancée de ce modèle permet des simulations plus naturelles des interactions entre particules, réduisant le nombre de paramètres numériques à utiliser dans le modèle. L’algorithme résultant est implémenté dans TrioCFD un code open-source conçu pour le calcul parallèle massif. La précision et la fiabilité du code de simulation ont été testées contre des références bien établies dans la littérature. De plus,la thèse inclut une simulation paramétrique d’un lit fluidisé à l’échelle de laboratoire, comparant la précision de l’algorithme aux résultats expérimentaux et numériques. Ces comparaisons démontrent que l’algorithme proposé reproduit correctement lesréférences établiesFluid particle flows hold significant importance in a variety of industrial applications, particularly in the context of third-generation concentrated solar power plants, where they can be used as both a heat transfer fluid and a storage medium. However, studying these flows presents considerable challenges due to the complex multiscale interactions governing them. Numerical simulation, particularly Direct Numerical Simulation (DNS) methods where the resolution is smaller than the particle diameter, emerges as a promising tool for better understanding these flows and aiding in the design of pilot-scale industrial applications. The increase in computational capabilities and the performance of numerical algorithms has made the particle resolved simulations of fluidized beds increasingly feasible for representative studies.In this thesis, we present a numerical method based on the one-fluid formulation. This method combines the front tracking method with the viscous penalty method to simulate fluid particle flow behaviors. The front tracking method employs a dual mesh system. This system effectively tracks the moving solid interfaces, represented as a moving mesh, across a fixed simulation grid, ensuring accuracy in representing the particle movements. The viscous penalty method, on the other hand, plays a pivotal role in ensuring the fidelity of rigid body motion within the particles. This is achieved by treating the fluid within the particles as an extremely viscous medium, thereby enabling the simulation to realistically mimic the behavior of fluid particles under various conditions.For short-term interactions between particles, a combined collision model is used. This model adeptly accounts for both viscous dissipation and solid dissipation, primarily due to lubrication effects and inelastic contacts between particles, respectively. The nuanced approach of this model allows for more natural simulations of particle interactions, reducing the reliance on arbitrary numerical parameters often seen in other models cited in the literature. The algorithm is implemented in TrioCFD an open-source framework designed for massively parallel computing.The accuracy and reliability of the simulation code were rigorously tested against well-established benchmarks in the literature. Furthermore, the thesis includes a parametric simulation of a lab-scale fluidized bed, comparing the accuracy of the algorithm against both experimental and numerical results. These comparisons demonstrate that the proposed algorithm aligns well with established benchmarks and exhibits good accuracy in its predictions
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Fry, Benjamin. "Modélisation multi-échelle d'un lit granulaire entraîné par un écoulement cisaillé." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0132.
Abstract:
Dans cette thèse, on étudie le transport granulaire par charriage en régime établi d’un lit de grains soumis à un écoulement de Couette laminaire pour un rapport de densité fluide-grain de 2.5 et une gamme de nombre de Reynolds particulaire, Re p [0.1, 10], et de nombre de Shields, [0.1,0.7]. Toutes les échelles de cet écoulement diphasique (à l’exception des effets de lubrification) sont décrites via la résolution numérique des équations de Navier-Stokes en prenant en compte la présence des particules par une méthode de frontières immergées (IBM) couplée à un solveur granulaire (méthode des éléments discrets - DEM) qui résout les équations de Newton pour chaque particule ainsi que les contacts et frottements entre grains (résolution à l’échelle microscopique). Un changement d’échelle est ensuite effectué afin d’obtenir une description de l’écoulement via des champs continus équivalents (description à l’échelle mésoscopique). Les simulations IBM-DEM permettent de quantifier chacun des termes du modèle dit mésoscopique et de caractériser la rhéologie de chaque phase ainsi que du mélange. On effectue finalement un second changement d’échelle afin de réduire l’écoulement de grains observé à une singularité, qui correspond à une condition limite du point de vue de l’écoulement du fluide. Cette condition est du type de Navier. Les simulations IBM-DEM montrent que la longueur dite de glissement "équivalente" est directement proportionnelle au nombre de ShieldsIn this work, we consider the steady transport of a granular medium by a laminar Couette flow for a fixed density ratio of 2.5 and a range of particle Reynolds number, Re p [0.1, 10], and Shields number [0.1, 0.7]. All scales of this two-phase flow are captured (except for the lubrication effects). By solving the Navier-Stokes equations, taking into account the presence of particles using an Immersed Boundary Method (IBM) coupled to a granular solver (Discrete Elements Method - DEM) which solves the Newton equations for each particle, in particular grain-grain interactions (resolution at the microscopic scale). Up-scaling is then performed to describe the flow via equivalent continuous quantities (description at the mesoscopic scale). IBM-DEM simulations allow to quantify all the terms of the so-called mesoscopic model and to characterize the rheology of each phase and that of the equivalent mixture. A second up-scaling is finally performed to reduce the granular flow to a singularity, which corresponds to a boundary condition from the fluid view point. The boundary condition is of Navier’s type. The IBM-DEM simulations suggest that the corresponding "equivalent" slip-lenght scales as
Book chapters on the topic "Multi-Phase granular flow":
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Topin, Vincent, Jean-Yves Delenne, Farhang Radjaï, and Frédéric Mabille. "Stress Transmission in a Multi-Phase Granular Packing." In Traffic and Granular Flow ’07, 659–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-77074-9_74.
Conference papers on the topic "Multi-Phase granular flow":
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Ryan, Emily M., Wei Xu, David DeCroix, Kringan Saha, E. David Huckaby, Sebastian Dartevelle, and Xin Sun. "Multi-Phase CFD Modeling of a Solid Sorbent Carbon Capture System." In ASME 2012 Fluids Engineering Division Summer Meeting collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/fedsm2012-72298.
Abstract:
Post-combustion solid sorbent carbon capture systems are being studied via computational modeling as part of the U.S. Department of Energy’s Carbon Capture Simulation Initiative (CCSI). The work focuses on computational modeling of device-scale multi-phase computational fluid dynamics (CFD) simulations for given carbon capture reactor configurations to predict flow properties, outlet compositions, temperature and pressure. The detailed outputs of the device-scale models provide valuable insight into the operation of new carbon capture devices and will help in the design and optimization of carbon capture systems. As a first step in this project we have focused on modeling a 1 kWe solid sorbent carbon capture system using the commercial CFD software ANSYS FLUENT®. Using the multi-phase models available in ANSYS FLUENT®, we are investigating the use of Eulerian-Eulerian and Eulerian-Lagrangian methods for modeling a fluidized bed carbon capture design. The applicability of the dense discrete phase method (DDPM) is being considered along with the more traditional Eulerian-Eulerian multi-phase model. In this paper we will discuss the operation of the 1 kWe solid sorbent system and the setup of the DDPM and Eulerian-Eulerian models used to simulate the system. The results of the hydrodynamics in the system will be discussed and the predictions of the DDPM and Eulerian-Eulerian simulations will be compared. A discussion of the sensitivity of the model to boundary and initial conditions, computational meshing, granular pressure, and drag sub-models will also be presented.
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Cristea, Eugen-Dan, and Pierangelo Conti. "Hybrid Eulerian Multiphase-Dense Discrete Phase Model Approach for Numerical Simulation of Dense Particle-Laden Turbulent Flows Within Vertical Multi-Stage Cyclone Heat Exchanger." In ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83058.
Abstract:
This article describes a CFD engineering application developed to investigate numerically the multiphase, non-isothermal, turbulent flow physics within the suspension preheater of a dry-process rotary cement kiln. The multi–stage cyclone preheater is a counter-current heat exchanger. We used the CFD flow solver ANSYS-Fluent R18.1. to accomplish this task. The hybrid Eulerian multiphase-dense discrete phase model is a coupled Eulerian-Lagrangian technique. The primary carrier-phase is treated as a continuum by solving the Navier-Stokes equations, while the secondary discrete dispersed-phase is solved by tracking the particle parcels through the calculated flow field. The multiphase turbulence of the carrier-phase is modeled using the Reynolds stress transport model. The dispersed-phase interactions are modeled through the specific collisions models provided by the kinetic theory of granular flow and/or discrete element method. The Eulerian multiphase-DDPM method provided a quiet stable solution for a medium/high mass loading (solid to gas mass ratio 0.89:1). The four-stage cyclone suspension preheater is analyzed for its operating performance i.e. overall pressure drop and global collection efficiency of cyclone stages, calcination degree at bottom cyclone stage, flue gas temperature at 1st. cyclone stage and availability to get more insight of very complex multi-phase flow patterns within this equipment. The set of industrial measurements, collected during a heat and mass balance of a dry process rotary cement kiln, were used to verify and to validate part of the simulation results.
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Huang, Jun, Guang Yin, Muk Chen Ong, and Xu Jia. "Numerical Investigation of Scour Beneath a Subsea Piggyback Pipeline." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18789.
Abstract:
Abstract In present study, two-dimensional numerical simulations have been carried out to investigate scour beneath a piggyback pipeline subjected to a subsea boundary layer flow using SedFoam (an open-source multi-dimensional Eulerian two-phase solver for sediment transport based on OpenFOAM). In the piggyback configuration, a small pipeline is attached on the upstream and downstream sides of a large pipeline. This form of piggyback can reduce the scour depth beneath the pipeline (Yang et al., 2019). In the solver, the turbulence Reynolds stress is resolved using a two-phase modified k-ε model. The particle stresses caused by the binary collisions and contacts are modeled by the kinetic theory for granular flow and a phenomenological frictional model, respectively. The effects of the locations of the small pipelines attached on the large pipeline on the scour and the surrounding flow field are discussed.
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Yin, Guang, Zhen Cheng, Shengnan Liu, and Muk Chen Ong. "Numerical Investigation of Scour Around Subsea Pipelines Near the Seabed." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-96069.
Abstract:
Abstract In the present study, two-phase flow simulations using SedFoam (an open-source multi-dimensional Eulerian two-phase solver based on OpenFOAM) are employed to investigate the scour phenomenon around pipelines in the vicinity of the seabed. A complete transport profile from the immobile bed, to slowly moving quasi-static bed and upper transport layers can be captured by the present model. The fluid Reynolds stress is modeled using the two-phase k-ε model. The particle stresses due to binary collisions and enduring contacts are modeled by kinetic theory for granular flow and a phenomenological frictional model, respectively. The model is first validated through a two-dimensional (2D) simulation of scour around a single pipeline near the seabed. The predicted time-dependent scour profiles as well as the scour depth are compared with the simulation results of Lee et al. (2016) and the experimental data reported by Mao (1986). A numerical experiment is then carried out to investigate the scour around the piggyback near the seabed. The effects of different locations of the small pipeline on the scour depth are studied.
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Xiao, Xianbin, Wei Wang, Hairui Yang, Hai Zhang, Jiansheng Zhang, Qing Liu, Junfu Lu, and Guangxi Yue. "Combustion Modeling of CFB Boiler Furnace Based on an Euler-Euler Approach." In 18th International Conference on Fluidized Bed Combustion. ASMEDC, 2005. http://dx.doi.org/10.1115/fbc2005-78040.
Abstract:
For the better design of large scale CFB boilers, reliable multi-dimensional modeling which can be used to predict the heterogeneous distributions of gas and solid concentration as well as temperature in the furnace is necessary and demanded. A model describing the complex combustion process in a CFB boiler furnace has been developed. The model consists of several essential sub-parts: the hydrodynamics of the bed, combustion of fuel, and overall mass balance of the furnace. In the computational fluid dynamics (CFD) study on hydrodynamics in a CFB boiler, the Euler-Euler approach is used, in which both gas and solid phases are considered as interpenetrating continua with the interaction through drag and energy dissipation caused by particle fluctuation. The constitutive equations for solid phase are derived from the kinetic theory of granular flow (KTGF). Some simplifications of the complicated theoretical equations with empirical correlations are adopted, to save computing time and skip the currently unknown phenomena. Drag coefficient between gas phase and solid phase is modified by the energy-minimization multi-scale (EMMS) principle. A simplified description of reaction process is also adopted. The present model was applied to predict the hydrodynamic and combustion behaviors in a commercial 135 MWe CFB boiler. Some primary results are obtained and discussed in comparison with the measured data. Prediction results agree with the experimental data in general, confirming the correctness of the model. More reliable experiments are needed for the model improvement in the future.
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Shi, Shaoping, Christopher Guenther, and Stefano Orsino. "Numerical Study of Coal Gasification Using Eulerian-Eulerian Multiphase Model." In ASME 2007 Power Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/power2007-22144.
Abstract:
Gasification converts the carbon-containing material into a synthesis gas (syngas) which can be used as a fuel to generate electricity or used as a basic chemical building block for a large number of uses in the petrochemical and refining industries. Based on the mode of conveyance of the fuel and the gasifying medium, gasification can be classified into fixed or moving bed, fluidized bed, and entrained flow reactors. Entrained flow gasifiers normally feature dilute flow with small particle size and can be successfully modeled with the Discrete Phase Method (DPM). For the other types, the Eulerian-Eulerian (E-E) or the so called two-fluid multiphase model is a more appropriate approach. The E-E model treats the solid phase as a distinct interpenetrating granular “fluid” and it is the most general-purposed multi-fluid model. This approach provides transient, three-dimensional, detailed information inside the reactor which would otherwise be unobtainable through experiments due to the large scale, high pressure and/or temperature. In this paper, a transient, three-dimensional model of the Power Systems Development Facility (PSDF) transport gasifier will be presented to illustrate how Computational Fluid Dynamics (CFD) can be used for large-scale complicated geometry with detailed physics and chemistry. In the model, eleven species are included in the gas phase while four pseudo-species are assumed in the solid phase. A total of sixteen reactions, both homogeneous (involving only gas phase species) and heterogeneous (involving species in both gas and solid phases), are used to model the coal gasification chemistry. Computational results have been validated against PSDF experimental data from lignite to bituminous coals under both air and oxygen blown conditions. The PSDF gasifier geometry was meshed with about 70,000, hexahedra-dominated cells. A total of six cases with different coal, feed gas, and/or operation conditions have been performed. The predicted and measured temperature profiles along the gasifier and gas compositions at the outlet agreed fairly well.
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Chen, Sheng, Haoyuan Kang, Mengke Wang, Cenfan Liu, Haitao Lin, and Juanbo Liu. "Reactive CFD Simulation of Fixed Coke Formation in an Industrial RFCC Riser Reactor." In ASME 2021 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/pvp2021-61671.
Abstract:
Abstract Severe fixed Coke in the industrial residue fluid catalytic cracking (RFCC) riser reactor often results in the reduction of product yield and unplanned unit shutdown. It is difficult to simultaneously depict physical and chemical formation of fixed coke near wall due to no approach and coking model. In this paper, the complex gas-solid-liquid three phase flow, mixing and cracking reaction are in agreement with the industrial data by 3D reactive simulation with multiphase Eulerian granular model coupling with the vaporization empirical correlation and the energy-minimization multi-scale (EMMS) drag and mass transfer models. A new coking index is developed to predict the formation possibility of fixed coke based on the 3D accurate simulation. The variations of coking profiles at different diameter of oil droplet are investigated. The results indicate that the fixed coke formation can be well depicted by the coking index. The predicted of fixed coke in the feed injection zone is same with the actual positions in industrial unit, which mainly located near the walls of the 0.5∼3.0m height above the feed nozzles and the circumferential between adjacent nozzles. The feed oil droplet size can improve the formation possibility of fixed coke.
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Deshpande, Kedar, Pravin Naphade, and Chad Wuest. "Advanced Computational Modeling for Estimating Safe Cuttings Load Through MPD Surface Equipment." In IADC/SPE Asia Pacific Drilling Technology Conference. SPE, 2021. http://dx.doi.org/10.2118/201074-ms.
Abstract:
Abstract The critical components of Managed Pressure Drilling (MPD) operations include surface manifold, surface chokes and the pipes connected to Mud Gas separators. The MPD surface equipment needs to safely handle a multiphase mixture of drilling mud, cuttings load and reservoir fluid influx during operations. The focus of this work is to establish safe cuttings load limit that can be handled by MPD system using advanced computational fluid dynamics (CFD) modeling approach. In MPD operations the surface choke is the key surface manifold component through which the fluid and cuttings flow before entering the Coriolis meter. Based on choke position only a certain volume and size of cuttings (cuttings load) can pass through chokes without causing unintentional pressure surges. In this work, Non-Newtonian fluid flow using Eulerian-Granular modeling approach is presented to understand the effects of cuttings load and different choke positions on the overall pressure drop through MPD surface manifold. Several CFD studies were conducted for different choke sizes, cuttings load and fluid properties to understand velocity profiles, cuttings accumulation and pressure drop across the MPD surface manifold. CFD results were first validated with available test data to generate confidence in CFD simulation model settings, good match was observed in pressure values between test and numerical results. Based on CFD simulations, charts were developed showing effect of operational parameters that help field personnel design the best surface equipment configuration, determine associated pressure drop and guard against the possibility of Non-Productive Time (NPT). CFD studies provided insights into cuttings accumulation and associated pressure drop change across choke for given operating conditions. Usage of advanced computational methods helped model the multi-phase flow with cuttings accurately and provided safe cuttings load estimation for given range of operational parameters.