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Author: Kun Xu Publisher: Cambridge University Press ISBN: 1108890512 Category : Technology & Engineering Languages : en Pages : 106
Book Description
This Element presents a unified computational fluid dynamics framework from rarefied to continuum regimes. The framework is based on the direct modelling of flow physics in a discretized space. The mesh size and time step are used as modelling scales in the construction of discretized governing equations. With the variation-of-cell Knudsen number, continuous modelling equations in different regimes have been obtained, and the Boltzmann and Navier-Stokes equations become two limiting equations in the kinetic and hydrodynamic scales. The unified algorithms include the discrete velocity method (DVM)–based unified gas-kinetic scheme (UGKS), the particlebased unified gas-kinetic particle method (UGKP), and the wave and particle–based unified gas-kinetic wave-particle method (UGKWP). The UGKWP is a multi-scale method with the particle for non-equilibrium transport and wave for equilibrium evolution. The particle dynamics in the rarefied regime and the hydrodynamic flow solver in the continuum regime have been unified according to the cell's Knudsen number.
Author: Kun Xu Publisher: Cambridge University Press ISBN: 1108890512 Category : Technology & Engineering Languages : en Pages : 106
Book Description
This Element presents a unified computational fluid dynamics framework from rarefied to continuum regimes. The framework is based on the direct modelling of flow physics in a discretized space. The mesh size and time step are used as modelling scales in the construction of discretized governing equations. With the variation-of-cell Knudsen number, continuous modelling equations in different regimes have been obtained, and the Boltzmann and Navier-Stokes equations become two limiting equations in the kinetic and hydrodynamic scales. The unified algorithms include the discrete velocity method (DVM)–based unified gas-kinetic scheme (UGKS), the particlebased unified gas-kinetic particle method (UGKP), and the wave and particle–based unified gas-kinetic wave-particle method (UGKWP). The UGKWP is a multi-scale method with the particle for non-equilibrium transport and wave for equilibrium evolution. The particle dynamics in the rarefied regime and the hydrodynamic flow solver in the continuum regime have been unified according to the cell's Knudsen number.
Author: Kun Xu Publisher: World Scientific Publishing Company Incorporated ISBN: 9789814623711 Category : Science Languages : en Pages : 318
Book Description
Direct Modeling for Computational Fluid Dynamics -- Introduction to Gas Kinetic Theory -- Introduction to Nonequilibrium Flow Simulations -- Gas Kinetic Scheme -- Unified Gas Kinetic Scheme -- Low Speed Microflow Studies -- High Speed Flow Studies -- Unified Gas Kinetic Scheme for Diatomic Gas -- Conclusion -- Appendix A: Non-dimensionalizing fluid dynamic variables -- Appendix B. Connection between BGK, Navier Stokes and Euler equations -- Appendix C. Moments of Maxwellian distribution function and expansion coefficients -- Appendix D. Flux evaluation through stationary and moving cell interfaces
Author: Joseph T. C. Liu Publisher: Cambridge University Press ISBN: 1108997791 Category : Technology & Engineering Languages : en Pages : 78
Book Description
In this Element, the gas-particle flow problem is formulated with momentum and thermal slip that introduces two relaxation times. Starting from acoustical propagation in a medium in equilibrium, the relaxation-wave equation in airfoil coordinates is derived though a Galilean transformation for uniform flow. Steady planar small perturbation supersonic flow is studied in detail according to Whitham's higher-order waves. The signals owing to wall boundary conditions are damped along the frozen-Mach wave, and are both damped and diffusive along an effective-intermediate Mach wave and diffusive along the equilibrium Mach wave where the bulk of the disturbance propagates. The surface pressure coefficient is obtained exactly for small-disturbance theory, but it is considerably simplified for the small particle-to-gas mass loading approximation, equivalent to a simple-wave approximation. Other relaxation-wave problems are discussed. Martian dust-storm properties in terms of gas-particle flow parameters are estimated.
Author: Iain D. Boyd Publisher: Cambridge University Press ISBN: 1107073448 Category : Science Languages : en Pages : 383
Book Description
7.1 Introduction -- 7.2 Rotational Energy Exchange Models -- 7.2.1 Constant Collision Number -- 7.2.2 The Parker Model -- 7.2.3 Variable Probability Exchange Model of Boyd -- 7.2.4 Nonequilibrium Direction Dependent Model -- 7.2.5 Model Results -- 7.3 Vibrational Energy Exchange Models -- 7.3.1 Constant Collision Number -- 7.3.2 The Millikan-White Model -- 7.3.3 Quantized Treatment for Vibration -- 7.3.4 Model Results -- 7.4 Dissociation Chemical Reactions -- 7.4.1 Total Collision Energy Model -- 7.4.2 Redistribution of Energy Following a Dissociation Reaction -- 7.4.3 Vibrationally Favored Dissociation Model -- 7.5 General Chemical Reactions -- 7.5.1 Reaction Rates and Equilibrium Constant -- 7.5.2 Backward Reaction Rates in DSMC -- 7.5.3 Three-Body Recombination Reactions -- 7.5.4 Post-Reaction Energy Redistribution and General Implementation -- 7.5.5 DSMC Solutions for Reacting Flows -- 7.6 Summary -- Appendix A: Generating Particle Properties -- Appendix B: Collisional Quantities -- Appendix C: Determining Post-Collision Velocities -- Appendix D: Macroscopic Properties -- Appendix E: Common Integrals -- References -- Index
Author: Ismail H. Tuncer Publisher: Springer Science & Business Media ISBN: 3540927441 Category : Mathematics Languages : en Pages : 489
Book Description
At the 19th Annual Conference on Parallel Computational Fluid Dynamics held in Antalya, Turkey, in May 2007, the most recent developments and implementations of large-scale and grid computing were presented. This book, comprised of the invited and selected papers of this conference, details those advances, which are of particular interest to CFD and CFD-related communities. It also offers the results related to applications of various scientific and engineering problems involving flows and flow-related topics. Intended for CFD researchers and graduate students, this book is a state-of-the-art presentation of the relevant methodology and implementation techniques of large-scale computing.
Author: K.J Bathe Publisher: Elsevier ISBN: 008052947X Category : Technology & Engineering Languages : en Pages : 2485
Book Description
Bringing together the world's leading researchers and practitioners of computational mechanics, these new volumes meet and build on the eight key challenges for research and development in computational mechanics.Researchers have recently identified eight critical research tasks facing the field of computational mechanics. These tasks have come about because it appears possible to reach a new level of mathematical modelling and numerical solution that will lead to a much deeper understanding of nature and to great improvements in engineering design.The eight tasks are: - The automatic solution of mathematical models - Effective numerical schemes for fluid flows - The development of an effective mesh-free numerical solution method - The development of numerical procedures for multiphysics problems - The development of numerical procedures for multiscale problems - The modelling of uncertainties - The analysis of complete life cycles of systems - Education - teaching sound engineering and scientific judgement Readers of Computational Fluid and Solid Mechanics 2003 will be able to apply the combined experience of many of the world's leading researchers to their own research needs. Those in academic environments will gain a better insight into the needs and constraints of the industries they are involved with; those in industry will gain a competitive advantage by gaining insight into the cutting edge research being carried out by colleagues in academia. Features - Bridges the gap between academic researchers and practitioners in industry - Outlines the eight main challenges facing Research and Design in Computational mechanics and offers new insights into the shifting the research agenda - Provides a vision of how strong, basic and exciting education at university can be harmonized with life-long learning to obtain maximum value from the new powerful tools of analysis
Author: Federico Toschi Publisher: Springer Nature ISBN: 3030233707 Category : Science Languages : en Pages : 313
Book Description
This open access book, published in the Soft and Biological Matter series, presents an introduction to selected research topics in the broad field of flowing matter, including the dynamics of fluids with a complex internal structure -from nematic fluids to soft glasses- as well as active matter and turbulent phenomena. Flowing matter is a subject at the crossroads between physics, mathematics, chemistry, engineering, biology and earth sciences, and relies on a multidisciplinary approach to describe the emergence of the macroscopic behaviours in a system from the coordinated dynamics of its microscopic constituents. Depending on the microscopic interactions, an assembly of molecules or of mesoscopic particles can flow like a simple Newtonian fluid, deform elastically like a solid or behave in a complex manner. When the internal constituents are active, as for biological entities, one generally observes complex large-scale collective motions. Phenomenology is further complicated by the invariable tendency of fluids to display chaos at the large scales or when stirred strongly enough. This volume presents several research topics that address these phenomena encompassing the traditional micro-, meso-, and macro-scales descriptions, and contributes to our understanding of the fundamentals of flowing matter. This book is the legacy of the COST Action MP1305 “Flowing Matter”.
Author: Kun Xu Publisher: World Scientific ISBN: 9814623733 Category : Technology & Engineering Languages : en Pages : 335
Book Description
Computational fluid dynamics (CFD) studies the flow motion in a discretized space. Its basic scale resolved is the mesh size and time step. The CFD algorithm can be constructed through a direct modeling of flow motion in such a space. This book presents the principle of direct modeling for the CFD algorithm development, and the construction unified gas-kinetic scheme (UGKS). The UGKS accurately captures the gas evolution from rarefied to continuum flows. Numerically it provides a continuous spectrum of governing equation in the whole flow regimes.
Author: G. A. Bird Publisher: ISBN: 9781492112907 Category : Monte Carlo method Languages : en Pages : 300
Book Description
Direct Simulation Monte Carlo is a well-established method for the computer simulation of a gas flow at the molecular level. While there is a limit to the size of the flow-field with respect to the molecular mean free path, personal computers now allow solutions well into the continuum flow regime. The method can be applied to basic problems in gas dynamics and practical applications range from microelectromechanics systems (MEMS) to astrophysical flows. DSMC calculations have assisted in the design of vacuum systems, including those for semiconductor manufacture, and of many space vehicles and missions. The method was introduced by the author fifty years ago and it has been the subject of two monographs that have been published by Oxford University Press. It is now twenty years since the second of these was written and, since that time, most DSMC procedures have been superseded or significantly modified. In addition, visual interactive DSMC application programs have been developed that have proved to be readily applicable by non-specialists to a wide variety of practical problems. The computational variables are set automatically within the code and the programs report whether or not the criteria for a good calculation have been met. This book is concerned with the theory behind the current DSMC molecular models and procedures, with their integration into general purpose programs, and with the validation and demonstration of these programs. The DSMC and associated programs, including all source codes, can be freely downloaded through links that are provided in the book. The main accompanying program is simply called the "DSMC program" and, in future versions of the book, it will be applicable to homogeneous (or zero-dimensional) flows through to three-dimensional flow. All DSMC simulations are time-accurate unsteady calculations, but the flow may become steady at large times. The current version of the DSMC code is applicable only to zero and one-dimensional flows and the older DS2V code is employed for the two-dimensional validation and demonstration cases. It is because of this temporary use of the older and well-proven program that the DS2V source code is made freely available for the first time. Most of the homogeneous flow cases are validation studies, but include internal mode relaxation studies and spontaneous and forced ignition leading to combustion in an oxygen-hydrogen mixture. The one-dimensional cases include the structure of a re-entry shock wave that takes into account electronic excitation as well as dissociation, recombination and exchange reactions. They also include a spherically imploding shock wave and a spherical blast wave. The two-dimensional and axially-symmetric demonstration cases range from a typical MEMS flow to aspects of the flow around rotating planets. Intermediate cases include the formation and structure of a combustion wave, a vacuum pump driven by thermal creep, a typical vacuum processing chamber, and the flow around a typical re-entry vehicle
Author: Kun Xu
Author: Kun Xu
Author: Kun Xu
Author: Joseph T. C. Liu
Author: Iain D. Boyd
Author: Ismail H. Tuncer
Author: Christopher E. Brennen
Author: K.J Bathe
Author: Federico Toschi
Author: Kun Xu
Author: G. A. Bird