Download or read book Extending Bubble induced Turbulence Modeling Applicability in CFD Through Incorporation of DNS Understanding written by Benjamin Lawrence Magolan and published by . This book was released on 2018 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: Precise knowledge and understanding of the multiphase flow distribution is essential for light water reactor design. Multiphase Computational Fluid Dynamics (M-CFD) modeling and simulation techniques provide three-dimensional resolution of complex flow structures, which can be used to improve operation and safety in current systems, while driving optimization and performance enhancement in next generation designs. Introducing bubbles into liquid flow dramatically modifies the turbulent kinetic energy profile. Examination of experimental and Direct Numerical Simulation (DNS) research reveals a complicated, incomplete, and conflicting picture of bubble-induced turbulence (BIT). Incorporating these physical mechanisms into a BIT model compatible within the Eulerian-Eulerian framework remains a formidable challenge. Two-equation BIT models share a general formulation, manifesting as additional source terms in traditional turbulence models to account for production and dissipation of bubble-induced turbulence. Existing formulations struggle with reliably predicting the turbulent kinetic energy profile, routinely yielding non-physical results that subsequently worsen mean flow predictions. The present work encompasses two research objectives that include (1) advancing the understanding of the complex effects bubbles pose on liquid turbulence, and (2) proposing an approach to incorporate these physical phenomena into a BIT closure relation. Greater understanding of two-phase turbulent mechanisms is advanced through statistical analysis of upward bubbly channel flow DNS data generated by Bolotnov and Lu/Tryggvason. The impact of bubble deformability on the resulting turbulent distributions, energy budgets, and scales are quantified and examined. A methodology that incorporates these fundamental mechanisms into a new BIT model is proposed. The closure comprises five components that include new turbulent viscosity and time-scale formulations in addition to optimized values for the modulation parameter, dissipation coefficient, and newly proposed turbulent viscosity multiplier. Model performance and improvement is confirmed through simulation of the entire Liu (1989) experimental database and comparison with existing closures. The model is incorporated into the Bubbly And Moderate void Fraction (BAMF) formulation (Sugrue et al., 2017) in order to deliver best practices and guidelines for application of momentum closures with BIT modeling. This is accomplished through redefinition of the Wobble number, calibration of expressions for the turbulent dispersion coefficient and lift inversion function, and assessment via simulation of experimental databases.
Download or read book Turbulence Modeling for CFD CD ROM written by David C. Wilcox and published by . This book was released on 2006 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bubbly Flows written by Martin Sommerfeld and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book summarises the outcom of a priority research programme: 'Analysis, Modelling and Computation of Multiphase Flows'. The results of 24 individual research projects are presented. The main objective of the research programme was to provide a better understanding of the physical basis for multiphase gas-liquid flows as they are found in numerous chemical and biochemical reactors. The research comprises steady and unsteady multiphase flows in three frequently found reactor configurations, namely bubble columns without interiors, airlift loop reactors, and aerated stirred vessels. For this purpose new and improved measurement techniques were developed. From the resulting knowledge and data, new and refined models for describing the underlying physical processes were developed, which were used for the establishment and improvement of analytic as well as numerical methods for predicting multiphase reactors. Thereby, the development, lay-out and scale-up of such processes should be possible on a more reliable basis.
Download or read book Turbulence Models and Their Application in Hydraulics written by Wolfgang Rodi and published by . This book was released on 1984 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mathematics of Large Eddy Simulation of Turbulent Flows written by Luigi Carlo Berselli and published by Springer Science & Business Media. This book was released on 2006 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: The LES-method is rapidly developing in many practical applications in engineering The mathematical background is presented here for the first time in book form by one of the leaders in the field
Download or read book Twenty Second Symposium on Naval Hydrodynamics written by National Research Council and published by National Academies Press. This book was released on 2000-03-02 with total page 1039 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Twenty-Second Symposium on Naval Hydrodynamics was held in Washington, D.C., from August 9-14, 1998. It coincided with the 100th anniversary of the David Taylor Model Basin. This international symposium was organized jointly by the Office of Naval Research (Mechanics and Energy Conversion S&T Division), the National Research Council (Naval Studies Board), and the Naval Surface Warfare Center, Carderock Division (David Taylor Model Basin). This biennial symposium promotes the technical exchange of naval research developments of common interest to all the countries of the world. The forum encourages both formal and informal discussion of the presented papers, and the occasion provides an opportunity for direct communication between international peers.
Download or read book Basic Fluid Mechanics written by David C. Wilcox and published by . This book was released on 2000 with total page 824 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulation of Unsteady Flows and Transition to Turbulence written by O. Pironneau and published by Cambridge University Press. This book was released on 1992-07-31 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: The workshop concentrated on the following turbulence test cases: T1 Boundary layer in an S-shaped duct; T2 Periodic array of cylinders in a channel; T3 Transition in a boundary layer under the influence of free-stream turbulence; T4 & T5: Axisymmetric confined jet flows.
Download or read book Computational Fluid Dynamics for Engineers written by Bengt Andersson and published by Cambridge University Press. This book was released on 2011-12-22 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational fluid dynamics, CFD, has become an indispensable tool for many engineers. This book gives an introduction to CFD simulations of turbulence, mixing, reaction, combustion and multiphase flows. The emphasis on understanding the physics of these flows helps the engineer to select appropriate models to obtain reliable simulations. Besides presenting the equations involved, the basics and limitations of the models are explained and discussed. The book combined with tutorials, project and power-point lecture notes (all available for download) forms a complete course. The reader is given hands-on experience of drawing, meshing and simulation. The tutorials cover flow and reactions inside a porous catalyst, combustion in turbulent non-premixed flow, and multiphase simulation of evaporation spray respectively. The project deals with design of an industrial-scale selective catalytic reduction process and allows the reader to explore various design improvements and apply best practice guidelines in the CFD simulations.
Download or read book Three Dimensional Flow in the Root Region of Wind Turbine Rotors written by Galih Bangga and published by kassel university press GmbH. This book was released on 2018-06-20 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the state of the art in the analyses of three-dimensional flow over rotating wind turbine blades. Systematic studies for wind turbine rotors with different sizes were carried out numerically employing three different simulation approaches, namely the Euler, URANS and DDES methods. The main mechanisms of the lift augmentation in the blade inboard region are described in detail. The physical relations between the inviscid and viscous effects are presented and evaluated, emphasizing the influence of the flow curvature on the resulting pressure distributions. Detailed studies concerning the lift augmentation for large wind turbine rotors are considered as thick inboard airfoils characterized by massive separation are desired to stronger contribute to power production. Special attention is given to the analyses of wind turbine loads and flow field that can be helpful for the interpretation of the occurring physical phenomena. The book is aimed at students, researchers, engineers and physicists dealing with wind engineering problems, but also for a wider audience involved in flow computations.
Download or read book Statistical Theory and Modeling for Turbulent Flows written by P. A. Durbin and published by Wiley-Blackwell. This book was released on 2001-03-12 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most natural and industrial flows are turbulent. The atmosphere and oceans, automobile and aircraft engines, all provide examples of this ubiquitous phenomenon. In recent years, turbulence has become a very lively area of scientific research and application, and this work offers a grounding in the subject of turbulence, developing both the physical insight and the mathematical framework needed to express the theory. Providing a solid foundation in the key topics in turbulence, this valuable reference resource enables the reader to become a knowledgeable developer of predictive tools. This central and broad ranging topic would be of interest to graduate students in a broad range of subjects, including aeronautical and mechanical engineering, applied mathematics and the physical sciences. The accompanying solutions manual to the text also makes this a valuable teaching tool for lecturers and for practising engineers and scientists in computational and experimental and experimental fluid dynamics.
Download or read book Fluid Mechanics for Engineers written by Meinhard T. Schobeiri and published by Springer Science & Business Media. This book was released on 2010-03-27 with total page 517 pages. Available in PDF, EPUB and Kindle. Book excerpt: The contents of this book covers the material required in the Fluid Mechanics Graduate Core Course (MEEN-621) and in Advanced Fluid Mechanics, a Ph. D-level elective course (MEEN-622), both of which I have been teaching at Texas A&M University for the past two decades. While there are numerous undergraduate fluid mechanics texts on the market for engineering students and instructors to choose from, there are only limited texts that comprehensively address the particular needs of graduate engineering fluid mechanics courses. To complement the lecture materials, the instructors more often recommend several texts, each of which treats special topics of fluid mechanics. This circumstance and the need to have a textbook that covers the materials needed in the above courses gave the impetus to provide the graduate engineering community with a coherent textbook that comprehensively addresses their needs for an advanced fluid mechanics text. Although this text book is primarily aimed at mechanical engineering students, it is equally suitable for aerospace engineering, civil engineering, other engineering disciplines, and especially those practicing professionals who perform CFD-simulation on a routine basis and would like to know more about the underlying physics of the commercial codes they use. Furthermore, it is suitable for self study, provided that the reader has a sufficient knowledge of calculus and differential equations. In the past, because of the lack of advanced computational capability, the subject of fluid mechanics was artificially subdivided into inviscid, viscous (laminar, turbulent), incompressible, compressible, subsonic, supersonic and hypersonic flows.
Download or read book Implicit Large Eddy Simulation written by Fernando F. Grinstein and published by Cambridge University Press. This book was released on 2007-07-30 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt: The numerical simulation of turbulent flows is a subject of great practical importance to scientists and engineers. The difficulty in achieving predictive simulations is perhaps best illustrated by the wide range of approaches that have been developed and are still being used by the turbulence modeling community. In this book the authors describe one of these approaches, Implicit Large Eddy Simulation (ILES). ILES is a relatively new approach that combines generality and computational efficiency with documented success in many areas of complex fluid flow. This book synthesizes the theoretical basis of the ILES methodology and reviews its accomplishments. ILES pioneers and lead researchers combine here their experience to present a comprehensive description of the methodology. This book should be of fundamental interest to graduate students, basic research scientists, as well as professionals involved in the design and analysis of complex turbulent flows.
Download or read book Boundary Layer Flows written by Vallampati Ramachandra Prasad and published by BoD – Books on Demand. This book was released on 2020-01-22 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by experts in the field, this book, "Boundary Layer Flows - Theory, Applications, and Numerical Methods" provides readers with the opportunity to explore its theoretical and experimental studies and their importance to the nonlinear theory of boundary layer flows, the theory of heat and mass transfer, and the dynamics of fluid. With the theory's importance for a wide variety of applications, applied mathematicians, scientists, and engineers - especially those in fluid dynamics - along with engineers of aeronautics, will undoubtedly welcome this authoritative, up-to-date book.
Download or read book Gas Turbine Blade Cooling written by Chaitanya D Ghodke and published by SAE International. This book was released on 2018-12-10 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gas turbines play an extremely important role in fulfilling a variety of power needs and are mainly used for power generation and propulsion applications. The performance and efficiency of gas turbine engines are to a large extent dependent on turbine rotor inlet temperatures: typically, the hotter the better. In gas turbines, the combustion temperature and the fuel efficiency are limited by the heat transfer properties of the turbine blades. However, in pushing the limits of hot gas temperatures while preventing the melting of blade components in high-pressure turbines, the use of effective cooling technologies is critical. Increasing the turbine inlet temperature also increases heat transferred to the turbine blade, and it is possible that the operating temperature could reach far above permissible metal temperature. In such cases, insufficient cooling of turbine blades results in excessive thermal stress on the blades causing premature blade failure. This may bring hazards to the engine's safe operation. Gas Turbine Blade Cooling, edited by Dr. Chaitanya D. Ghodke, offers 10 handpicked SAE International's technical papers, which identify key aspects of turbine blade cooling and help readers understand how this process can improve the performance of turbine hardware.
Download or read book Turbulent Reactive Flows written by R. Borghi and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 958 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent reactive flows are of common occurrance in combustion engineering, chemical reactor technology and various types of engines producing power and thrust utilizing chemical and nuclear fuels. Pollutant formation and dispersion in the atmospheric environment and in rivers, lakes and ocean also involve interactions between turbulence, chemical reactivity and heat and mass transfer processes. Considerable advances have occurred over the past twenty years in the understanding, analysis, measurement, prediction and control of turbulent reactive flows. Two main contributors to such advances are improvements in instrumentation and spectacular growth in computation: hardware, sciences and skills and data processing software, each leading to developments in others. Turbulence presents several features that are situation-specific. Both for that reason and a number of others, it is yet difficult to visualize a so-called solution of the turbulence problem or even a generalized approach to the problem. It appears that recognition of patterns and structures in turbulent flow and their study based on considerations of stability, interactions, chaos and fractal character may be opening up an avenue of research that may be leading to a generalized approach to classification and analysis and, possibly, prediction of specific processes in the flowfield. Predictions for engineering use, on the other hand, can be foreseen for sometime to come to depend upon modeling of selected features of turbulence at various levels of sophistication dictated by perceived need and available capability.
Download or read book Modelling Fluid Flow written by János Vad and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modelling Fluid Flow presents invited lectures, workshop summaries and a selection of papers from a recent international conference CMFF '03 on fluid technology. The lectures follow the current evolution and the newest challenges of the computational methods and measuring techniques related to fluid flow. The workshop summaries reflect the recent trends, open questions and unsolved problems in the mutually inspiring fields of experimental and computational fluid mechanics. The papers cover a wide range of fluids engineering, including reactive flow, chemical and process engineering, environmental fluid dynamics, turbulence modelling, numerical methods, and fluid machinery.
