Taylor Length-scale Size Particles in Isotropic Turbulence PDF Download
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Author: Francesco Lucci
Publisher:
ISBN: 9781124517681
Category :
Languages : en
Pages : 149
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Book Description
The present study investigates the two-way coupling effects of finite-size solid spherical particles on decaying isotropic turbulence using an immersed boundary method. study of the interactions between finite-size particles andisotropic turbulence. The conventional point particle assumption is valid only in the case of particles with a diameter, dp, much smaller than the Kolmogorov length scale, %eta. In a simulation with particles of diameter dp/sub” %eta the flow around each particle needs to be resolved. In this study, we use a method similar to that of Uhlmann(2005) that adapts the Immersed Boundary(IB) Method developed by Peskin to simulate the flow around suspended spherical solid particles. The main idea of the method is to distribute a number of Lagrangian points uniformly over the surface of the particle. A force is applied at each Lagrangian point to represent the momentum exchange between the particle and the surrounding fluid. An analytic three-point delta function is used to distribute the force to the Eulerian grid points saddling the spherical surface to satisfy the no-slip condition at each Lagrangian point. Decaying turbulence is simulated in a periodic box with a uniform mesh of up to (512)sup3/sup grid points and an initial microscale Reynolds number of up to Resub%lambda 0= 110. We compare the single phase flow (SPF) with particle-laden flows with particles of different diameters. The density of the particle varies from 2.56 to 10 times that of the fluid. The effects of the particles on the temporal development of turbulence kinetic energy E(t), its dissipation rate e(t), its two-way coupling rate of change Psi_p(t) and frequency spectra E(%omega) are discussed. In this study, in contrast to particles with d_p %eta, particles with d_p %eta always increase the dissipation rate of turbulence kinetic energy, e(t). In addition, \Psi_p(t) is always positive, whereas it can be positive or negative for particles with d_p
Author: Francesco Lucci
Publisher:
ISBN: 9781124517681
Category :
Languages : en
Pages : 149
Get Book Here
Book Description
The present study investigates the two-way coupling effects of finite-size solid spherical particles on decaying isotropic turbulence using an immersed boundary method. study of the interactions between finite-size particles andisotropic turbulence. The conventional point particle assumption is valid only in the case of particles with a diameter, dp, much smaller than the Kolmogorov length scale, %eta. In a simulation with particles of diameter dp/sub” %eta the flow around each particle needs to be resolved. In this study, we use a method similar to that of Uhlmann(2005) that adapts the Immersed Boundary(IB) Method developed by Peskin to simulate the flow around suspended spherical solid particles. The main idea of the method is to distribute a number of Lagrangian points uniformly over the surface of the particle. A force is applied at each Lagrangian point to represent the momentum exchange between the particle and the surrounding fluid. An analytic three-point delta function is used to distribute the force to the Eulerian grid points saddling the spherical surface to satisfy the no-slip condition at each Lagrangian point. Decaying turbulence is simulated in a periodic box with a uniform mesh of up to (512)sup3/sup grid points and an initial microscale Reynolds number of up to Resub%lambda 0= 110. We compare the single phase flow (SPF) with particle-laden flows with particles of different diameters. The density of the particle varies from 2.56 to 10 times that of the fluid. The effects of the particles on the temporal development of turbulence kinetic energy E(t), its dissipation rate e(t), its two-way coupling rate of change Psi_p(t) and frequency spectra E(%omega) are discussed. In this study, in contrast to particles with d_p %eta, particles with d_p %eta always increase the dissipation rate of turbulence kinetic energy, e(t). In addition, \Psi_p(t) is always positive, whereas it can be positive or negative for particles with d_p
Author: Doychev, Todor
Publisher: KIT Scientific Publishing
ISBN: 3731503077
Category : Engineering (General). Civil engineering (General)
Languages : en
Pages : 272
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Book Description
This book contributes to the fundamental understanding of the physical mechanisms that take place in pseudo turbulent particulate flows. In the present work we have considered the sedimentation of large numbers of spherical rigid particles in an initially quiescent flow field. We have performed direct numerical simulations employing an immersed boundary method for the representation of the fluid-solid interface. The results evidence that depending on the particle settling regime (i.e. Galileo number and particle-to-fluid density ratio) the particles may exhibit strong inhomogeneous spatial distribution. It is found that the particles are preferentially located in regions with downward fluid motion. The particles inside clusters experience larger settling velocities than the average. The flow in all flow cases is observed to exhibit characteristic features of pseudo-turbulence. The particle-induced flow field is further found to be highly anisotropic with dominant vertical components. The results indicate that, in the present flow configurations, the collective and mobility effects play significant role for the particle and fluid motion.
Author: Manuel García-Villalba
Publisher: Springer Nature
ISBN: 3030428222
Category : Technology & Engineering
Languages : en
Pages : 478
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Book Description
This book gathers the proceedings of the 12th instalment in the bi-annual Workshop series on Direct and Large Eddy Simulation (DLES), which began in 1994 and focuses on modern techniques used to simulate turbulent flows based on the partial or full resolution of the instantaneous turbulent flow structure. With the rapidly expanding capacities of modern computers, this approach has attracted more and more interest over the years and will undoubtedly be further enhanced and applied in the future. Hybrid modelling techniques based on a combination of LES and RANS approaches also fall into this category and are covered as well. The goal of the Workshop was to share the state of the art in DNS, LES and related techniques for the computation and modelling of turbulent and transitional flows. The respective papers highlight the latest advances in the prediction, understanding and control of turbulent flows in academic and industrial applications.
Author: David Ting
Publisher: Academic Press
ISBN: 0128039833
Category : Science
Languages : en
Pages : 258
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Book Description
Basics of Engineering Turbulence introduces flow turbulence to engineers and engineering students who have a fluid dynamics background, but do not have advanced knowledge on the subject. It covers the basic characteristics of flow turbulence in terms of its many scales. The author uses a pedagogical approach to help readers better understand the fundamentals of turbulence scales, especially how they are derived through the order of magnitude analysis. This book is intended for those who have an interest in flowing fluids. It provides some background, though of limited scope, on everyday flow turbulence, especially in engineering applications. The book begins with the 'basics' of turbulence which is necessary for any reader being introduced to the subject, followed by several examples of turbulence in engineering applications. This overall approach gives readers all they need to grasp both the fundamentals of turbulence and its applications in practical instances. - Focuses on the basics of turbulence for applications in engineering and industrial settings - Provides an understanding of concepts that are often challenging, such as energy distribution among the turbulent structures, the effective diffusivity, and the theory behind turbulence scales - Offers a user-friendly approach with clear-and-concise explanations and illustrations, as well as end-of-chapter problems
Author: Michel O. Deville
Publisher: Springer
ISBN: 366243489X
Category : Science
Languages : en
Pages : 196
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Book Description
The book presents a snapshot of the state-of-art in the field of turbulence modeling and covers the latest developments concerning direct numerical simulations, large eddy simulations, compressible turbulence, coherent structures, two-phase flow simulation and other related topics. It provides readers with a comprehensive review of both theory and applications, describing in detail the authors’ own experimental results. The book is based on the proceedings of the third Turbulence and Interactions Conference (TI 2012), which was held on June 11-14 in La Saline-les-Bains, La Réunion, France and includes both keynote lectures and outstanding contributed papers presented at the conference. This multifaceted collection, which reflects the conference ́s emphasis on the interplay of theory, experiments and computing in the process of understanding and predicting the physics of complex flows and solving related engineering problems, offers a practice-oriented guide for students, researchers and professionals in the field of computational fluid dynamics, turbulence modeling and related areas.
Author: Leonid I. Zaichik
Publisher: John Wiley & Sons
ISBN: 3527626263
Category : Science
Languages : en
Pages : 318
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Book Description
The only work available to treat the theory of turbulent flow with suspended particles, this book also includes a section on simulation methods, comparing the model results obtained with the PDF method to those obtained with other techniques, such as DNS, LES and RANS. Written by experienced scientists with background in oil and gas processing, this book is applicable to a wide range of industries -- from the petrol industry and industrial chemistry to food and water processing.
Author: Shankar Subramaniam
Publisher: Academic Press
ISBN: 0323901344
Category : Technology & Engineering
Languages : en
Pages : 588
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Book Description
Modelling Approaches and Computational Methods for Particle-laden Turbulent Flows introduces the principal phenomena observed in applications where turbulence in particle-laden flow is encountered while also analyzing the main methods for analyzing numerically. The book takes a practical approach, providing advice on how to select and apply the correct model or tool by drawing on the latest research. Sections provide scales of particle-laden turbulence and the principal analytical frameworks and computational approaches used to simulate particles in turbulent flow. Each chapter opens with a section on fundamental concepts and theory before describing the applications of the modelling approach or numerical method. Featuring explanations of key concepts, definitions, and fundamental physics and equations, as well as recent research advances and detailed simulation methods, this book is the ideal starting point for students new to this subject, as well as an essential reference for experienced researchers. - Provides a comprehensive introduction to the phenomena of particle laden turbulent flow - Explains a wide range of numerical methods, including Eulerian-Eulerian, Eulerian-Lagrange, and volume-filtered computation - Describes a wide range of innovative applications of these models
Author: Stéphane Vincent
Publisher: Springer Nature
ISBN: 3031092651
Category : Technology & Engineering
Languages : en
Pages : 314
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Book Description
The book provides basic and recent research insights concerning the small scale modeling and simulation of turbulent multi-phase flows. By small scale, it has to be understood that the grid size for the simulation is smaller than most of the physical time and space scales of the problem. Small scale modeling of multi-phase flows is a very popular topic since the capabilities of massively parallel computers allows to go deeper into the comprehension and characterization of realistic flow configurations and at the same time, many environmental and industrial applications are concerned such as nuclear industry, material processing, chemical reactors, engine design, ocean dynamics, pollution and erosion in rivers or on beaches. The work proposes a complete and exhaustive presentation of models and numerical methods devoted to small scale simulation of incompressible turbulent multi-phase flows from specialists of the research community. Attention has also been paid to promote illustrations and applications, multi-phase flows and collaborations with industry. The idea is also to bring together developers and users of different numerical approaches and codes to share their experience in the development and validation of the algorithms and discuss the difficulties and limitations of the different methods and their pros and cons. The focus will be mainly on fixed-grid methods, however adaptive grids will be also partly broached, with the aim to compare and validate the different approaches and models.
Author:
Publisher: ScholarlyEditions
ISBN: 1464963746
Category : Technology & Engineering
Languages : en
Pages : 3933
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Book Description
Issues in Mechanical Engineering / 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Mechanical Engineering. The editors have built Issues in Mechanical Engineering: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Mechanical Engineering in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Mechanical Engineering: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Author: Luis Blay Esteban
Publisher: Springer
ISBN: 3030281361
Category : Technology & Engineering
Languages : en
Pages : 163
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Book Description
This book studies the dynamics of 2D objects moving through turbulent fluids. It examines the decay of turbulence over extended time scales, and compares the dynamics of non-spherical particles moving through still and turbulent fluids. The book begins with an introduction to the project, its aims, and its relevance for industrial applications. It then discusses the movement of planar particles in quiescent fluid, and presents the numerous methodologies used to measure it. The book also presents a detailed analysis of the falling style of irregular particles, which makes it possible to estimate particle trajectory and wake morphology based on frontal geometry. In turn, the book provides the results of an analysis of physically constrained decaying turbulence in a laboratory setting. These results suggest that large-scale cut-off in numerical simulations can result in severe bias in the computed turbulent kinetic energy for long waiting times. Combining the main text with a wealth of figures and sketches throughout, the book offers an accessible guide for all engineering students with a basic grasp of fluid mechanics, while the key findings will also be of interest to senior researchers.
