Contribution à l'étude des forces exercées par un liquide sur une bulle de gaz PDF Download

Author: Ahmed Naciri
Publisher:
ISBN:
Category :
Languages : fr
Pages : 94

View

Book Description
La modélisation des écoulements diphasiques à bulles se heurte à un certain nombre de difficultés liées essentiellement à la méconnaissance des mécanismes physiques à l'échelle de la bulle, en particulier la force exercée par un liquide en mouvement non uniforme sur la bulle et les effets d'interaction hydrodynamique entre bulles. De ce fait, nous nous sommes intéressés dans ce travail à trois mécanismes de base : -La quantification de la force de portance, soit expérimentalement dans le cas d'une bulle placée dans un écoulement en rotation ; ceci nous a permis d'évaluer le coefficient de portance et de montrer que sa valeur est comprise entre celle obtenue pour un fluide parfait et celle déduite des simulations numériques pour une sphère solide ; soit théoriquement pour un corps axisymétrique place dans un écoulement faiblement cisaillé de fluide parfait ou on a montre l'égalité entre le coefficient de portance et celui de masse ajoutée. -La détermination expérimentale de la quantité de fluide déplacé par une bulle isolée et la comparaison de ce phénomène à celui de masse ajoutée. II s'est avéré dans cette étude que lorsque l'interface de la bulle demeure approximativement sphérique on a l'égalité entre ces deux quantités. -L'évaluation de la force mutuelle d'interaction entre deux bulles de même diamètre montant dans un liquide au repos. Les résultats sont comparés à la théorie de fluide parfait où on montre que celle-ci décrit correctement l'interaction lorsque la répartition du champ de pression constitue l'effet dominant. Ceci tombe en défaut lorsque les effets du sillage sont ressentis par l'une des deux bulles. L'utilisation du résultat concernant la force de portance dans un code de calcul développé au Laboratoire montre que la démarche suivie dans le cadre de ce travail peut aider à l'amélioration des lois de fermeture utilisées dans les modélisations des écoulements a bulles.

Author: Eric Loth
Publisher: Cambridge University Press
ISBN: 1009365401
Category : Science
Languages : en
Pages : 574

View

Book Description
A modern presentation of multiphase flow, from basic principles to state-of-the-art research. Explains dispersed fluid dynamics for bubbles, drops, or solid particles, incorporating detailed theory, experiments, simulations, and models while considering applications and recent cutting-edge advances. The book demonstrates the importance of multiphase flow in engineering and natural systems, considering particle size distributions, shapes and trajectories as well as deformation of fluid particles and multiphase flow numerical methods. The scope of the book also includes coupling physics between particles and turbulence through dispersion and modulation, and specific phenomena such as gravitational settling and collisions for solid particles, drops and bubbles. Featuring over eighty homework problems for each of the primary chapters, including theory-based and engineering application questions. The comprehensive coverage will give the reader a solid grounding for multiphase flow research and design, applicable to current and future engineering. This is an ideal resource for graduate students, researchers and professionals.

Author: Arie Biesheuvel
Publisher: Springer Science & Business Media
ISBN: 9401149860
Category : Technology & Engineering
Languages : en
Pages : 502

View

Book Description
In Fascination of Fluid Dynamics contains a collection of papers by international experts in hydrodynamics, based on oral presentations at a symposium held in honour of Professor Leen van Wijngaarden on his 65th birthday. The book begins with a personal sketch of his life and scientific career. It continues with a mixture of papers that address recent developments in various branches of fluid mechanics. Many of the papers cover different aspects of multiphase flows: bubble dynamics, cavitation, bubbles and particles in turbulent flows, suspension flows, and wave phenomena in fluidised beds. Other topics that are addressed include: dynamics of jets, shock waves, MHD turbulence, selforganisation phenomena in 2D turbulence, vortex rings and the thermodynamics of tropical cyclones. This edited volume will be valuable reading for researchers, engineers and students interested in hydrodynamics, and in particular in multiphase flows.

Author: Nikolay Ivanov Kolev
Publisher: Springer Science & Business Media
ISBN: 3642207499
Category : Technology & Engineering
Languages : en
Pages : 337

View

Book Description
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: Nikolay Ivanov Kolev
Publisher: Springer Science & Business Media
ISBN: 3540698329
Category : Technology & Engineering
Languages : en
Pages : 789

View

Book Description
Multi-phase flows are part of our natural environment such as tornadoes, typhoons, air and water pollution and volcanic activities as well as part of industrial technology such as power plants, combustion engines, propulsion systems, or chemical and biological industry. The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. In its third extended edition this monograph contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations, providing a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present first volume the fundamentals of multiphase dynamics are provided. This third edition includes various updates, extensions and improvements in all book chapters.

Author: Mamoru Ishii
Publisher: Springer Science & Business Media
ISBN: 1441979859
Category : Technology & Engineering
Languages : en
Pages : 518

View

Book Description
Thermo-fluid Dynamics of Two-Phase Flow, Second Edition is focused on the fundamental physics of two-phase flow. The authors present the detailed theoretical foundation of multi-phase flow thermo-fluid dynamics as they apply to: Nuclear reactor transient and accident analysis; Energy systems; Power generation systems; Chemical reactors and process systems; Space propulsion; Transport processes. This edition features updates on two-phase flow formulation and constitutive equations and CFD simulation codes such as FLUENT and CFX, new coverage of the lift force model, which is of particular significance for those working in the field of computational fluid dynamics, new equations and coverage of 1 dimensional drift flux models and a new chapter on porous media formulation.

Author: Nikolay Ivanov Kolev
Publisher: Springer Science & Business Media
ISBN: 3540698353
Category : Technology & Engineering
Languages : en
Pages : 698

View

Book Description
Multi-phase flows are part of our natural environment such as tornadoes, typhoons, air and water pollution and volcanic activities as well as part of industrial technology such as power plants, combustion engines, propulsion systems, or chemical and biological industry. The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. In its third extended edition this book contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations. This book provides a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present second volume the mechanical and thermal interactions in multiphase dynamics are provided. This third edition includes various updates, extensions, improvements and corrections.

Author: Martín López de Bertodano
Publisher: Springer
ISBN: 3319449680
Category : Technology & Engineering
Languages : en
Pages : 367

View

Book Description
This book addresses the linear and nonlinear two-phase stability of the one-dimensional Two-Fluid Model (TFM) material waves and the numerical methods used to solve it. The TFM fluid dynamic stability is a problem that remains open since its inception more than forty years ago. The difficulty is formidable because it involves the combined challenges of two-phase topological structure and turbulence, both nonlinear phenomena. The one dimensional approach permits the separation of the former from the latter.The authors first analyze the kinematic and Kelvin-Helmholtz instabilities with the simplified one-dimensional Fixed-Flux Model (FFM). They then analyze the density wave instability with the well-known Drift-Flux Model. They demonstrate that the Fixed-Flux and Drift-Flux assumptions are two complementary TFM simplifications that address two-phase local and global linear instabilities separately. Furthermore, they demonstrate with a well-posed FFM and a DFM two cases of nonlinear two-phase behavior that are chaotic and Lyapunov stable. On the practical side, they also assess the regularization of an ill-posed one-dimensional TFM industrial code. Furthermore, the one-dimensional stability analyses are applied to obtain well-posed CFD TFMs that are either stable (RANS) or Lyapunov stable (URANS), with the focus on numerical convergence.

Author: Nikolay Ivanov Kolev
Publisher: Springer Science & Business Media
ISBN: 354071443X
Category : Technology & Engineering
Languages : en
Pages : 314

View

Book Description
In order to allow the application of the theory from all the three volumes also to processes in combustion engines a systematic set of internally consistent state equations for diesel fuel gas and liquid valid in broad range of changing pressure and temperature are provided also in Volume 3. Erlangen, October 2006 Nikolay Ivanov Kolev Table of contents 1 Some basics of the single-phase boundary layer theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1. 1 Flow over plates, velocity profiles, share forces, heat transfer. . . . . . . . . . . . . . . . . . . . 1 1. 1. 1 Laminar flow over the one site of a plane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1. 1. 2 Turbulent flow parallel to plane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. 2 Steady state flow in pipes with circular cross sections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. 2. 1 Hydraulic smooth wall surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1. 2. 2 Transition region. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1. 2. 3 Complete rough region. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1. 2. 4 Heat transfer to fluid in a pipe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 1. 3 Transient flow in pipes with circular cross sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Nomenclature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2 Introduction to turbulence of multi-phase flows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2. 1 Basic ideas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2. 2 Isotropy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 2. 3 Scales, eddy viscosity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2. 3. 1 Small scale turbulent motion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2. 3. 2 Large scale turbulent motion, Kolmogorov-Pandtl expression. . . . . . . . . 42 2. 4 k-eps framework. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Nomenclature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 3 Sources for fine resolution outside the boundary layer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3. 1 Bulk sources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3. 1. 1 Deformation of the velocity field. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3. 1. 2 Blowing and suction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Author: American Institute of Aeronautics and Astronautics
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1112

View

Book Description