Buoyancy Driven Flows

Autore: Eric Chassignet
Editore: Cambridge University Press
ISBN: 1107079993
Grandezza: 63,46 MB
Formato: PDF
Vista: 8635
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Buoyancy is one of the main forces driving flows on our planet, especially in the oceans and atmosphere. These flows range from buoyant coastal currents to dense overflows in the ocean, and from avalanches to volcanic pyroclastic flows on the Earth's surface. This book brings together contributions by leading world scientists to summarize our present theoretical, observational, experimental and modeling understanding of buoyancy-driven flows. Buoyancy-driven currents play a key role in the global ocean circulation and in climate variability through their impact on deep-water formation. Buoyancy-driven currents are also primarily responsible for the redistribution of fresh water throughout the world's oceans. This book is an invaluable resource for advanced students and researchers in oceanography, geophysical fluid dynamics, atmospheric science and the wider Earth sciences who need a state-of-the-art reference on buoyancy-driven flows.

Simulation Of Laminar Buoyancy Driven Flows In An Enclosure

Autore: EMEL SELAMET
Editore:
ISBN:
Grandezza: 40,69 MB
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rectangular cavity, three cells are found in the wide section.

Buoyancy Driven Flow In Fluid Saturated Porous Media Near A Bounding Surface

Autore: Hitoshi Sakamoto
Editore: Springer
ISBN: 3319898876
Grandezza: 75,38 MB
Formato: PDF
Vista: 958
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This Brief reports on heat transfer from a solid boundary in a saturated porous medium. Experiments reveal overall heat transfer laws when the flow along the wall is driven by buoyancy produced by large temperature differences, and mathematical analysis using advanced volume-averaging techniques produce estimates of how heat is dispersed in the porous zone. Engineers, hydrologists and geophysicists will find the results valuable for validation of laboratory and field tests, as well as testing their models of dispersion of heat and mass in saturated media.

Analysis Of Buoyancy Driven Flow In The Rocom Test Facility

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ISBN:
Grandezza: 23,37 MB
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Abstract: In emergency core cooling (ECC) situations after a loss of coolant accident, cold ECC water is injected into the hot water of the cold leg and downcomer. Temperature distributions near the wall and temperature gradients in time are important to be known for the assessment of thermal stresses. Numerous experiments were realized in the test facility ROCOM of the Helmholz Zentrum Dresden- Rossendorf, Dresden, Germany to investigate the effects of density differences between the primary loop inventory and the ECC water on the mixing in the downcomer. In 2005, an experiment with 5% flow rate in loop 1 and 10% density difference between ECC and loop water were compared to CFD calculations with Trio_U. In this paper, the same experiment is analyzed here with the TrioCFD code, taking into account 10 years of code and hardware development. The comparison of the LES to the experiment is globally satisfying. However, the calculation shows important turbulent fluctuations overestimating the measurements at the upper and lower downcomer sensors. Besides this, the resistance of the perforated drum seems to be under predicted. For further studies, a key issue seems to be an improved finer meshing of the perforated drum and of the wall near region of the downcomer.

Buoyancy Driven Flows

Autore: H. S. Takhar
Editore:
ISBN:
Grandezza: 47,10 MB
Formato: PDF
Vista: 4646
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Physics Of Buoyant Flows

Autore: Verma Mahendra Kumar
Editore: World Scientific
ISBN: 9813237813
Grandezza: 68,14 MB
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Vista: 1694
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Gravity pervades the whole universe; hence buoyancy drives fluids everywhere including those in the atmospheres and interiors of planets and stars. Prime examples of such flows are mantle convection, atmospheric flows, solar convection, dynamo process, heat exchangers, airships and hot air balloons. In this book we present fundamentals and applications of thermal convection and stratified flows. Buoyancy brings in extremely rich phenomena including waves and instabilities, patterns, chaos, and turbulence. In this book we present these topics in a systematic manner. First we present a unified treatment of linear theory that yields waves and thermal instability for stably and unstably-stratified flows respectively. We extend this analysis to include rotation and magnetic field. We also describe nonlinear saturation and pattern formation in Rayleigh-Bénard convection. The second half of the book is dedicated to buoyancy-driven turbulence, both in stably-stratified flow and in thermal convection. We describe the spectral theory including energy flux and show that the thermally-driven turbulence is similar to hydrodynamic turbulence. We also describe large-scale quantities like Reynolds and Nusselt numbers, flow anisotropy, and the dynamics of flow structures, namely flow reversals. Thus, this book presents all the major aspects of the buoyancy-driven flows in a coherent manner that would appeal to advanced graduate students and researchers.

Buoyancy Effects In Fluids

Autore: J. S. Turner
Editore: Cambridge University Press
ISBN: 9780521297264
Grandezza: 30,12 MB
Formato: PDF
Vista: 5631
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The phenomena treated in this book all depend on the action of gravity on small density differences in a non-rotating fluid. The author gives a connected account of the various motions which can be driven or influenced by buoyancy forces in a stratified fluid, including internal waves, turbulent shear flows and buoyant convection. This excellent introduction to a rapidly developing field, first published in 1973, can be used as the basis of graduate courses in university departments of meteorology, oceanography and various branches of engineering. This edition is reprinted with corrections, and extra references have been added to allow readers to bring themselves up to date on specific topics. Professor Turner is a physicist with a special interest in laboratory modelling of small-scale geophysical processes. An important feature is the superb illustration of the text with many fine photographs of laboratory experiments and natural phenomena.

Buoyancy Driven Two Phase Countercurrent Flow

Autore: Kris Hamilton Lillibridge
Editore:
ISBN:
Grandezza: 28,56 MB
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Vista: 5150
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Experimental And Modeling Study Of Capillary Buoyancy Driven Flow Of Surrogate Co2 Through Intermediate Scale Sand Tanks

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Grandezza: 69,22 MB
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Abstract: The role of capillary forces during buoyant migration of CO2 is critical towards plume immobilization during post-injection of geological carbon sequestration. However, the inherent heterogeneity of most candidate reservoirs makes it very challenging to evaluate the effects of capillary forces on the storage capacity of these formations and to assess in-situ plume evolution. Given the technical challenges in characterizing deep reservoir's migration and trapping phenomena, the development of carefully controlled laboratory experiments allows recreating the interplay of governing forces that are expected in-situ. Visual observations, complemented by saturation measurements across homogeneous and heterogeneous sand packs, provide direct insight into capillary/buoyancy-dominated flow processes, allowing assessment of predictive ability of existing and new two-phase flow simulators.

Multidisciplinary Design Approach And Safety Analysis Of Adsr Cooled By Buoyancy Driven Flows

Autore: Carlos Alberto Ceballos Castillo
Editore: IOS Press
ISBN: 9781586037208
Grandezza: 59,75 MB
Formato: PDF
Vista: 7861
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"The energy consumption in the world is directly related to the economical growth. The International Energy Agency estimates a doubling increase of electricity demands in the next 25 years (Energy Outlook, 2004). Somehow, this growth must be satisfied without destroying the ecological equilibrium of our planet. For this reason, all sorts of energy resources, which are potential pollutants for the environment are being investigated, and their technologies improved, plus new renewable energies are developed. It is also evident that renewables will take several decades before they are able to substitute the present capacity and even more, to cope with the future energy demands. Nuclear energy is an air pollution free technology with the potential to satisfy the worlds energy demands for many centuries. However, some concerns about the use of nuclear energy have to be further developed in order to recognize nuclear energy as a sustainable option. This book deals with concerns such as the use of nuclear energy for weapons, the risk of accidents with radioactivity release and the waste management."

Simulation Of Multi Body Buoyant Flows

Autore: Reza Karimi
Editore:
ISBN:
Grandezza: 72,96 MB
Formato: PDF, ePub, Mobi
Vista: 8119
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Effect Of Buoyancy Driven Natural Convection In A Rock Pit Mine Air Preconditioning System Acting As A Large Scale Thermal Energy Storage Mass

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Editore:
ISBN:
Grandezza: 40,44 MB
Formato: PDF
Vista: 2583
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Highlights: Novel conjugate heat transfer and fluid dynamics model for thermal energy storage. Validation against experimental data. Evaluating buoyancy-driven natural convection effects. Increasing air flow rate is an effective technique to improve energy storage capacity. System performance can be augmented through optimum selection of intake trenches. Abstract: Underground mining is among the most energy-intensive industries and ventilation comprises a significant portion of the energy demands of this important industry. Using the vast volume of broken rock, left in a decommissioned mine pit, as a thermal energy storage mass has enormous potential to lower ventilation-related energy costs in deep underground mines. This approach facilitates moderating seasonal air temperature variations. Seasonal thermal energy storage is a cost-effective solution to improve cooling and heating process efficiencies, thereby reducing associated costs. Temperature gradients observed in the proposed storage system suggest the presence of a natural convection heat transfer mechanism that is buoyancy-driven. The effect of natural convection and a variety of heat transfer mechanisms were modeled and simulation results and field-data measurements were compared. The conjugate heat transfer and fluid flow model that was developed considers the porous rock mass in the rock-pit along with the air (i.e. fluid) blanketing the top surface. The effects of rock size, permeability and porosity were studied. It was observed that, for the range of porosities (from 0.45 to 0.20), these parameters have a small effect on the outlet air temperature and the performance of thermal storage phenomenon. The novel model compares forced (from ventilation fan) and natural (result of buoyancy) convection. Further, it incorporates the effect of design factors, such as air trench positions and flow rate of ventilated air, on energy savings.

Flow In Porous Rocks

Autore: Andrew W. Woods
Editore: Cambridge University Press
ISBN: 1107065852
Grandezza: 56,55 MB
Formato: PDF, ePub, Mobi
Vista: 3167
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Provides simplified models explaining flows in heterogeneous rocks, their physics and energy-production processes, for researchers, energy-industry professionals and graduate students.

Fundamental Mechanics Of Fluids Third Edition

Autore: Iain G. Currie
Editore: CRC Press
ISBN: 0203910540
Grandezza: 23,61 MB
Formato: PDF, Kindle
Vista: 8287
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Retaining the features that made previous editions perennial favorites, Fundamental Mechanics of Fluids, Third Edition illustrates basic equations and strategies used to analyze fluid dynamics, mechanisms, and behavior, and offers solutions to fluid flow dilemmas encountered in common engineering applications. The new edition contains completely reworked line drawings, revised problems, and extended end-of-chapter questions for clarification and expansion of key concepts. Includes appendices summarizing vectors, tensors, complex variables, and governing equations in common coordinate systems Comprehensive in scope and breadth, the Third Edition of Fundamental Mechanics of Fluids discusses: Continuity, mass, momentum, and energy One-, two-, and three-dimensional flows Low Reynolds number solutions Buoyancy-driven flows Boundary layer theory Flow measurement Surface waves Shock waves

Modeling Atmospheric And Oceanic Flows

Autore: Thomas von Larcher
Editore: John Wiley & Sons
ISBN: 1118855922
Grandezza: 27,93 MB
Formato: PDF, ePub, Docs
Vista: 9757
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Modeling Atmospheric and Oceanic Flows: Insights from Laboratory Experiments and Numerical Simulations provides a broad overview of recent progress in using laboratory experiments and numerical simulations to model atmospheric and oceanic fluid motions. This volume not only surveys novel research topics in laboratory experimentation, but also highlights recent developments in the corresponding computational simulations. As computing power grows exponentially and better numerical codes are developed, the interplay between numerical simulations and laboratory experiments is gaining paramount importance within the scientific community. The lessons learnt from the laboratory–model comparisons in this volume will act as a source of inspiration for the next generation of experiments and simulations. Volume highlights include: Topics pertaining to atmospheric science, climate physics, physical oceanography, marine geology and geophysics Overview of the most advanced experimental and computational research in geophysics Recent developments in numerical simulations of atmospheric and oceanic fluid motion Unique comparative analysis of the experimental and numerical approaches to modeling fluid flow Modeling Atmospheric and Oceanic Flows will be a valuable resource for graduate students, researchers, and professionals in the fields of geophysics, atmospheric sciences, oceanography, climate science, hydrology, and experimental geosciences.

Tackling Turbulent Flows In Engineering

Autore: Anupam Dewan
Editore: Springer Science & Business Media
ISBN: 9783642147678
Grandezza: 59,23 MB
Formato: PDF, ePub, Mobi
Vista: 2173
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The emphasis of this book is on engineering aspects of fluid turbulence. The book explains for example how to tackle turbulence in industrial applications. It is useful to several disciplines, such as, mechanical, civil, chemical, aerospace engineers and also to professors, researchers, beginners, under graduates and post graduates. The following issues are emphasized in the book: - Modeling and computations of engineering flows: The author discusses in detail the quantities of interest for engineering turbulent flows and how to select an appropriate turbulence model; Also, a treatment of the selection of appropriate boundary conditions for the CFD simulations is given. - Modeling of turbulent convective heat transfer: This is encountered in several practical situations. It basically needs discussion on issues of treatment of walls and turbulent heat fluxes. - Modeling of buoyancy driven flows, for example, smoke issuing from chimney, pollutant discharge into water bodies, etc

On The Meaning Of Mixing Efficiency For Buoyancy Driven Mixing In Stratified Turbulentflows

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ISBN:
Grandezza: 16,71 MB
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Abstract : The concept of a mixing efficiency is widely used to relate the amount of irreversible diabatic mixing in a stratified flow to the amount of energy available to support mixing. This common measure of mixing in a flow is based on the change in the background potential energy, which is the minimum gravitational potential energy of the fluid that can be achieved by an adiabatic rearrangement of the instantaneous density field. However, this paper highlights examples of mixing that is primarily 'buoyancy-driven' (i.e. energy is released to the flow predominantly from a source of available potential energy) to demonstrate that the mixing efficiency depends not only on the specific characteristics of the turbulence in the region of the flow that is mixing, but also on the density profile in regions remote from where mixing physically occurs. We show that this behaviour is due to the irreversible and direct conversion of available potential energy into background potential energy in those remote regions (a mechanism not previously described). This process (here termed 'relabelling') occurs without requiring either a local flow or local mixing, or any other process that affects the internal energy of that fluid. Relabelling is caused by initially available potential energy, associated with identifiable parcels of fluid, becoming dynamically inaccessible to the flow due to mixing elsewhere. These results have wider relevance to characterising mixing in stratified turbulent flows, including those involving an external supply of kinetic energy.

Buoyancy Induced Wall Flow Due To Fire In A Room

Autore: Yogesh Jaluria
Editore:
ISBN:
Grandezza: 55,75 MB
Formato: PDF, ePub, Docs
Vista: 6040
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A study of buoyancy-driven flow generated adjacent to the vertical walls of a room due to fire in the room has been carried out. The boundary layer flow that arises over the vertical walls due to the resulting difference between the wall and gas temperatures was analyzed, employing the integral analysis method. The flow rate, momentum and convected energy in the downward flow that arises in the heated upper layer and those in the upward flow that is generated in the cooler lower layer were determined. The separation point and the region near it where the flow starts separating from the wall are studied. Though more detailed and more accurate computations are included, an approximate method for evaluating the wall effects for a two-layer model and for an experimental study is outlined.

The Finite Element Method For Fluid Dynamics

Autore: Olek C Zienkiewicz
Editore: Elsevier
ISBN: 008045559X
Grandezza: 45,92 MB
Formato: PDF
Vista: 8983
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Dealing with general problems in fluid mechanics, convection diffusion, compressible and incompressible laminar and turbulent flow, shallow water flows and waves, this is the leading text and reference for engineers working with fluid dynamics in fields including aerospace engineering, vehicle design, thermal engineering and many other engineering applications. The new edition is a complete fluids text and reference in its own right. Along with its companion volumes it forms part of the indispensable Finite Element Method series. New material in this edition includes sub-grid scale modelling; artificial compressibility; full new chapters on turbulent flows, free surface flows and porous medium flows; expanded shallow water flows plus long, medium and short waves; and advances in parallel computing. A complete, stand-alone reference on fluid mechanics applications of the FEM for mechanical, aeronautical, automotive, marine, chemical and civil engineers. Extensive new coverage of turbulent flow and free surface treatments