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An Improved Multiscale Model For Dilute Turbulent Gas Particle Flows Based On The Equilibration Of Energy Concept
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Book Synopsis An Improved Multiscale Model for Dilute Turbulent Gas Particle Flows Based on the Equilibration of Energy Concept by : Ying Xu
Download or read book An Improved Multiscale Model for Dilute Turbulent Gas Particle Flows Based on the Equilibration of Energy Concept written by Ying Xu and published by . This book was released on 2004 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many particle-laden flows in engineering applications involve turbulent gas flows. Modeling multiphase turbulent flows is an important research topic with applications in fluidized beds and particle conveying. A predictive multiphase turbulence model can help CFD codes to be more useful for engineering applications, such as the scale-up in the design of circulating fluidized combustor and coal gasifications. It is reasonable to expect that multiphase turbulence models should at least satisfy some basic modeling and performance criteria and give reasonable predictions for the canonical problems in dilute particle-laden turbulent flows. In this research, a comparative assessment of predictions from Simonin and Ahmadi's turbulence models is performed with direct numerical simulation (DNS) for two canonical problems in particle-laden turbulent flows. Based on the comparative assessment, some criteria and the areas for model improvement are identified: (i) model for interphase TKE transfer, especially the time scale of interphase TKE transfer, and (ii) correct prediction of TKE evolution with variation of particle Stokes number. Some deficiencies that are identified in the Simonin and Ahmadi models limit the applicability. A new multiphase turbulence model, the Equilibration of Energy Model (EEM), is proposed in this work. In EEM, a multiscale interaction time scale is proposed to account for the interaction of a particle with a range of eddy sizes. EEM shows good agreement with the DNS results for particle-laden istropic turbulence. For particle-laden homogeneous shear flows, model predictions from EEM can be further improved if the dissipation rate in fluid phase is modeled with more accuracy. This new time scale is incorporated in the interphase TKE transfer terms of the Simonin and Ahmadi models. For canonical problems in particle-laden turbulent flows, this time scale improves the predictions from these two models. Although EEM is a simple model, it has a clear physical interpretation and gives reasonable predictions for two canonical problems in particle-laden turbulent flows. It can be a useful engineering tool for CFD calculations of gas-solid two phase flows.
Book Synopsis An Improved Multiscale Model for Dilute Turbulent Gas Particle Flows Based on the Equilibration of Energy Concept by :
Download or read book An Improved Multiscale Model for Dilute Turbulent Gas Particle Flows Based on the Equilibration of Energy Concept written by and published by . This book was released on 2004 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many particle-laden flows in engineering applications involve turbulent gas flows. Modeling multiphase turbulent flows is an important research topic with applications in fluidized beds and particle conveying. A predictive multiphase turbulence model can help CFD codes to be more useful for engineering applications, such as the scale-up in the design of circulating fluidized combustor and coal gasifications. In engineering applications, the particle volume fraction can vary from dilute (10sup-4
Author :American Society of Mechanical Engineers. Fluids Engineering Division. Summer Meeting Publisher : ISBN 13 : Total Pages :828 pages Book Rating :4.3/5 (91 download)
Book Synopsis Proceedings of the ASME Fluids Engineering Division Summer Meeting by : American Society of Mechanical Engineers. Fluids Engineering Division. Summer Meeting
Download or read book Proceedings of the ASME Fluids Engineering Division Summer Meeting written by American Society of Mechanical Engineers. Fluids Engineering Division. Summer Meeting and published by . This book was released on 2005 with total page 828 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Master's Theses Directories written by and published by . This book was released on 2005 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Education, arts and social sciences, natural and technical sciences in the United States and Canada".
Book Synopsis Commencement by : Iowa State University
Download or read book Commencement written by Iowa State University and published by . This book was released on 2004 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Multiscale and Multiresolution Approaches in Turbulence by : Pierre Sagaut
Download or read book Multiscale and Multiresolution Approaches in Turbulence written by Pierre Sagaut and published by World Scientific. This book was released on 2006 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique book gives a general unified presentation of the use of the multiscale/multiresolution approaches in the field of turbulence. The coverage ranges from statistical models developed for engineering purposes to multiresolution algorithms for the direct computation of turbulence. It provides the only available up-to-date reviews dealing with the latest and most advanced turbulence models (including LES, VLES, hybrid RANS/LES, DES) and numerical strategies.The book aims at providing the reader with a comprehensive description of modern strategies for turbulent flow simulation, ranging from turbulence modeling to the most advanced multilevel numerical methods.
Book Synopsis New Approaches in Modeling Multiphase Flows and Dispersion in Turbulence, Fractal Methods and Synthetic Turbulence by : F.C.G.A. Nicolleau
Download or read book New Approaches in Modeling Multiphase Flows and Dispersion in Turbulence, Fractal Methods and Synthetic Turbulence written by F.C.G.A. Nicolleau and published by Springer Science & Business Media. This book was released on 2011-10-29 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains a collection of the main contributions from the first five workshops held by Ercoftac Special Interest Group on Synthetic Turbulence Models (SIG42. It is intended as an illustration of the sig’s activities and of the latest developments in the field. This volume investigates the use of Kinematic Simulation (KS) and other synthetic turbulence models for the particular application to environmental flows. This volume offers the best syntheses on the research status in KS, which is widely used in various domains, including Lagrangian aspects in turbulence mixing/stirring, particle dispersion/clustering, and last but not least, aeroacoustics. Flow realizations with complete spatial, and sometime spatio-temporal, dependency, are generated via superposition of random modes (mostly spatial, and sometime spatial and temporal, Fourier modes), with prescribed constraints such as: strict incompressibility (divergence-free velocity field at each point), high Reynolds energy spectrum. Recent improvements consisted in incorporating linear dynamics, for instance in rotating and/or stably-stratified flows, with possible easy generalization to MHD flows, and perhaps to plasmas. KS for channel flows have also been validated. However, the absence of "sweeping effects" in present conventional KS versions is identified as a major drawback in very different applications: inertial particle clustering as well as in aeroacoustics. Nevertheless, this issue was addressed in some reference papers, and merits to be revisited in the light of new studies in progress.
Book Synopsis Investigations on Mesoscale Structure in Gas–Solid Fluidization and Heterogeneous Drag Model by : Cheng Chen
Download or read book Investigations on Mesoscale Structure in Gas–Solid Fluidization and Heterogeneous Drag Model written by Cheng Chen and published by Springer. This book was released on 2015-10-14 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explores the Energy Minimization Multi-scale (EMMS) theory and the drag model for heterogeneous gas-solid fluidized flows. The results show that the cluster density plays a critical role with regard to drag. A novel cluster model is proposed and indicates that the profile of cluster density is single-peaked with the maximum value located at solid concentrations of 0.1~0.15. The EMMS theory is improved with the cluster model and an accurate drag model is developed. The model’s universality is achieved by investigating the relationship between the heterogeneity and flow patterns. The drag model is subsequently verified numerically and experimentally.
Book Synopsis Modeling Complex Turbulent Flows by : Manuel D. Salas
Download or read book Modeling Complex Turbulent Flows written by Manuel D. Salas and published by Springer Science & Business Media. This book was released on 1999-04-30 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence modeling both addresses a fundamental problem in physics, 'the last great unsolved problem of classical physics,' and has far-reaching importance in the solution of difficult practical problems from aeronautical engineering to dynamic meteorology. However, the growth of supercom puter facilities has recently caused an apparent shift in the focus of tur bulence research from modeling to direct numerical simulation (DNS) and large eddy simulation (LES). This shift in emphasis comes at a time when claims are being made in the world around us that scientific analysis itself will shortly be transformed or replaced by a more powerful 'paradigm' based on massive computations and sophisticated visualization. Although this viewpoint has not lacked ar ticulate and influential advocates, these claims can at best only be judged premature. After all, as one computational researcher lamented, 'the com puter only does what I tell it to do, and not what I want it to do. ' In turbulence research, the initial speculation that computational meth ods would replace not only model-based computations but even experimen tal measurements, have not come close to fulfillment. It is becoming clear that computational methods and model development are equal partners in turbulence research: DNS and LES remain valuable tools for suggesting and validating models, while turbulence models continue to be the preferred tool for practical computations. We believed that a symposium which would reaffirm the practical and scientific importance of turbulence modeling was both necessary and timely.
Book Synopsis Dilute Turbulent Gas-solid Flow with Particle Interactions and Turbulence Modulation by : Eduardo Jose Bolio
Download or read book Dilute Turbulent Gas-solid Flow with Particle Interactions and Turbulence Modulation written by Eduardo Jose Bolio and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Predictive Modeling of Particle-laden Turbulent Flows. Final Report by :
Download or read book Predictive Modeling of Particle-laden Turbulent Flows. Final Report written by and published by . This book was released on 1993 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Earlier work of Sinclair and Jackson which treats the laminar flow of gas-solid suspensions is extended to model dilute turbulent flow. The random particle motion, often exceeding the turbulent fluctuations in the gas, is obtained using a model based on kinetic theory of granular materials. A two-equation low Reynolds number turbulence model is, modified to account for the presence of the dilute particle phase. Comparisons of the model predictions with available experimental data for the mean and fluctuating velocity profiles for both phases indicate that the resulting theory captures many of the flow features observed in the pneumatic transport of large particles. The model predictions did not manifest an extreme sensitivity to the degree of inelasticity in the particle-particle collisions for the range of solid loading ratios investigated.
Book Synopsis Theory and Modeling of Dispersed Multiphase Turbulent Reacting Flows by : Lixing Zhou
Download or read book Theory and Modeling of Dispersed Multiphase Turbulent Reacting Flows written by Lixing Zhou and published by Butterworth-Heinemann. This book was released on 2018-01-25 with total page 343 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theory and Modeling of Dispersed Multiphase Turbulent Reacting Flows gives a systematic account of the fundamentals of multiphase flows, turbulent flows and combustion theory. It presents the latest advances of models and theories in the field of dispersed multiphase turbulent reacting flow, covering basic equations of multiphase turbulent reacting flows, modeling of turbulent flows, modeling of multiphase turbulent flows, modeling of turbulent combusting flows, and numerical methods for simulation of multiphase turbulent reacting flows, etc. The book is ideal for graduated students, researchers and engineers in many disciplines in power and mechanical engineering. - Provides a combination of multiphase fluid dynamics, turbulence theory and combustion theory - Covers physical phenomena, numerical modeling theory and methods, and their applications - Presents applications in a wide range of engineering facilities, such as utility and industrial furnaces, gas-turbine and rocket engines, internal combustion engines, chemical reactors, and cyclone separators, etc.
Book Synopsis Modeling and Simulation of Turbulent Mixing and Reaction by : Daniel Livescu
Download or read book Modeling and Simulation of Turbulent Mixing and Reaction written by Daniel Livescu and published by Springer Nature. This book was released on 2020-02-19 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights recent research advances in the area of turbulent flows from both industry and academia for applications in the area of Aerospace and Mechanical engineering. Contributions include modeling, simulations and experiments meant for researchers, professionals and students in the area.
Book Synopsis Mesoscale Modeling in Chemical Engineering Part II by :
Download or read book Mesoscale Modeling in Chemical Engineering Part II written by and published by Academic Press. This book was released on 2016-02-16 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mesoscale Modeling in Chemical Engineering, a volume in the Advances in Chemical Engineering series provides the reader with personal views of authorities in the field. Subjects covered are not limited to the classical chemical engineering disciplines, with contributions connecting chemical engineering to related scientific fields, thus providing new ideas for additional thought. The book balances well developed areas such as process industry, transformation of materials, energy, and environmental issues with areas where applications of chemical engineering are more recent or emerging. - Contains reviews by leading authorities in the respective areas - Presents Up-to-date reviews of latest techniques in modeling of catalytic processes - Includes a mix of US and European authors, as well as academic/industrial/research institute perspectives - Contains the critical connections between computation and experimental methods
Book Synopsis Multiphase Flow Dynamics 4 by : Nikolay Ivanov Kolev
Download or read book Multiphase Flow Dynamics 4 written by Nikolay Ivanov Kolev and published by Springer Science & Business Media. This book was released on 2011-09-24 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present Volume 4 of the successful monograh package “Multiphase Flow Dynamics”is devoted to selected Chapters of the multiphase fluid dynamics that are important for practical applications but did not find place in the previous volumes. The state of the art of the turbulence modeling in multiphase flows is presented. As introduction, some basics of the single phase boundary layer theory including some important scales and flow oscillation characteristics in pipes and rod bundles are presented. Then the scales characterizing the dispersed flow systems are presented. The description of the turbulence is provided at different level of complexity: simple algebraic models for eddy viscosity, simple algebraic models based on the Boussinesq hypothesis, modification of the boundary layer share due to modification of the bulk turbulence, modification of the boundary layer share due to nucleate boiling. The role of the following forces on the mathematical description of turbulent flows is discussed: the lift force, the lubrication force in the wall boundary layer, and the dispersion force. A pragmatic generalization of the k-eps models for continuous velocity field is proposed containing flows in large volumes and flows in porous structures. A Methods of how to derive source and sinks terms for multiphase k-eps models is presented. A set of 13 single- and two phase benchmarks for verification of k-eps models in system computer codes are provided and reproduced with the IVA computer code as an example of the application of the theory. This methodology is intended to help other engineers and scientists to introduce this technology step-by-step in their own engineering practice. In many practical application gases are solved in liquids under given conditions, released under other conditions and therefore affecting technical processes for good of for bad. Useful information on the solubility of oxygen, nitrogen, hydrogen and carbon dioxide in water under large interval of pressures and temperatures is collected, and appropriate mathematical approximation functions are provided. In addition methods for the computation of the diffusion coefficients are described. With this information solution and dissolution dynamics in multiphase fluid flows can be analyzed. For this purpose the non-equilibrium absorption and release on bubble, droplet and film surfaces under different conditions is mathematically described. A systematic set of internally consistent state equations for diesel fuel gas and liquid valid in broad range of changing pressure and temperature is provided. This new second edition includes various updates, extensions, improvements and corrections. In many practical application gases are solved in liquids under given conditions, released under other conditions and therefore affecting technical processes for good of for bad. Useful information on the solubility of oxygen, nitrogen, hydrogen and carbon dioxide in water under large interval of pressures and temperatures is collected, and appropriate mathematical approximation functions are provided. In addition methods for the computation of the diffusion coefficients are described. With this information solution and dissolution dynamics in multiphase fluid flows can be analyzed. For this purpose the non-equilibrium absorption and release on bubble, droplet and film surfaces under different conditions is mathematically described. A systematic set of internally consistent state equations for diesel fuel gas and liquid valid in broad range of changing pressure and temperature is provided. This new second edition includes various updates, extensions, improvements and corrections.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722646417 Total Pages :56 pages Book Rating :4.6/5 (464 download)
Book Synopsis Modeling of Turbulent Swirling Flows by : National Aeronautics and Space Administration (NASA)
Download or read book Modeling of Turbulent Swirling Flows written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-13 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aircraft engine combustors generally involve turbulent swirling flows in order to enhance fuel-air mixing and flame stabilization. It has long been recognized that eddy viscosity turbulence models are unable to appropriately model swirling flows. Therefore, it has been suggested that, for the modeling of these flows, a second order closure scheme should be considered because of its ability in the modeling of rotational and curvature effects. However, this scheme will require solution of many complicated second moment transport equations (six Reynolds stresses plus other scalar fluxes and variances), which is a difficult task for any CFD implementations. Also, this scheme will require a large amount of computer resources for a general combustor swirling flow. This report is devoted to the development of a cubic Reynolds stress-strain model for turbulent swirling flows, and was inspired by the work of Launder's group at UMIST. Using this type of model, one only needs to solve two turbulence equations, one for the turbulent kinetic energy k and the other for the dissipation rate epsilon. The cubic model developed in this report is based on a general Reynolds stress-strain relationship. Two flows have been chosen for model evaluation. One is a fully developed rotating pipe flow, and the other is a more complex flow with swirl and recirculation. Shih, Tsan-Hsing and Zhu, Jiang and Liou, William and Chen, Kuo-Huey and Liu, Nan-Suey and Lumley, John L. Glenn Research Center...
