Download or read book Baroclinic Vortices in Rotating Stratified Shearing Flows written by Pedram Hassanzadeh and published by . This book was released on 2013 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large coherent vortices are abundant in geophysical and astrophysical flows. They play significant roles in the Earth's oceans and atmosphere, the atmosphere of gas giants, such as Jupiter, and the protoplanetary disks around forming stars. These vortices are essentially three-dimensional (3D) and baroclinic, and their dynamics are strongly influenced by the rotation and density stratification of their environments. This work focuses on improving our understanding of the physics of 3D baroclinic vortices in rotating and continuously stratified flows using 3D spectral simulations of the Boussinesq equations, as well as simplified mathematical models. The first chapter discusses the big picture and summarizes the results of this work. In Chapter 2, we derive a relationship for the aspect ratio (i.e., vertical half-thickness over horizontal length scale) of steady and slowly-evolving baroclinic vortices in rotating stratified fluids. We show that the aspect ratio is a function of the Brunt-Vaisala frequencies within the vortex and outside the vortex, the Coriolis parameter, and the Rossby number of the vortex. This equation is basically the gradient-wind equation integrated over the vortex, and is significantly different from the previously proposed scaling laws that find the aspect ratio to be only a function of the properties of the background flow, and independent of the dynamics of the vortex. Our relation is valid for cyclones and anticyclones in either the cyclostrophic or geostrophic regimes; it works with vortices in Boussinesq fluids or ideal gases, and non-uniform background density gradient. The relation for the aspect ratio has many consequences for quasi-equilibrium vortices in rotating stratified flows. For example, cyclones must have interiors more stratified than the background flow (i.e., super-stratified), and weak anticyclones must have interiors less stratified than the background (i.e., sub-stratified). In addition, this equation is useful to infer the height and internal stratification of some astrophysical and geophysical vortices because direct measurements of their vertical structures are difficult. We verify our relation for the aspect ratio with numerical simulations for a wide variety of families of vortices, including: vortices that are initially in (dissipationless) equilibrium and then evolve due to an imposed weak viscous dissipation or density radiation; anticyclones created by the geostrophic adjustment of a patch of locally-mixed density; cyclones created by fluid suction from a small localized region; vortices created from the remnants of the violent breakups of columnar vortices; and weakly non-axisymmetric vortices. The values of the aspect ratios of our numerically-computed vortices validate our theoretically-derived relationship for aspect ratio, and generally they differ significantly from the values obtained from the much-cited conjecture that the aspect ratio of quasi-geostrophic vortices is equal to the ratio of the Coriolis parameter to the Brunt-Vaisala frequency of the background flow. In Chapter 3, we show numerically and experimentally that localized suction in rotating continuously stratified flows produces three-dimensional baroclinic cyclones. As expected from Chapter 2, the interiors of these cyclones are super-stratified. Suction, modeled as a small spherical sink in the simulations, creates an anisotropic flow toward the sink with directional dependence changing with the ratio of the Coriolis parameter to the Brunt-Vaisala frequency. Around the sink, this flow generates cyclonic vorticity and deflects isopycnals so that the interior of the cyclone becomes super-stratified. The super-stratified region is visualized in the companion experiments that we helped to design and analyze using the synthetic schlieren technique. Once the suction stops, the cyclones decay due to viscous dissipation in the simulations and experiments. The numerical results show that the vertical velocity of viscously decaying cyclones flows away from the cyclone's midplane, while the radial velocity flows toward the cyclone's center. This observation is explained based on the cyclo-geostrophic balance. This vertical velocity mixes the flow inside and outside of cyclone and reduces the super-stratification. We speculate that the predominance of anticyclones in geophysical and astrophysical flows is due to the fact that anticyclones require sub-stratification, which occurs naturally by mixing, while cyclones require super-stratification. In Chapter 4, we show that a previously unknown instability creates space-filling lattices of 3D turbulent baroclinic vortices in linearly-stable, rotating, stratified shear flows. The instability starts from a newly discovered family of easily-excited critical layers. This new family, named the baroclinic critical layer, has singular vertical velocities; the traditional family of (barotropic) critical layer has singular stream-wise velocities and is hard to excite. In our simulations, the baroclinic critical layers in rotating stably-stratified linear shear are excited by small-volume, small-amplitude vortices or waves. The excited baroclinic critical layers then intensify by drawing energy from the background shear and roll-up into large coherent 3D vortices that excite new critical layers and vortices. The vortices self-similarly replicate to create lattices of turbulent vortices. These vortices persist for all time and are called zombie vortices because they can occur in the dead zones of protoplanetary disks. The self-replication of zombie vortices can de-stabilize the otherwise linearly and finite-amplitude stable Keplerian shear and lead to the formation of stars and planets.
Download or read book Dynamics of Vortex Structures in a Stratified Rotating Fluid written by Mikhail A. Sokolovskiy and published by Springer Science & Business Media. This book was released on 2013-08-28 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents an extensive analysis of the dynamics of discrete and distributed baroclinic vortices in a multi-layer fluid that characterizes the main features of the large and mesoscales dynamics of the atmosphere and the ocean. It widely covers the case of hetonic situations as well as the case of intrathermocline vortices that are familiar in oceanographic and of recognized importance for heat and mass transfers. Extensive typology of such baroclinic eddies is made and analysed with the help of theoretical development and numerical computations. As a whole it gives an overview and synthesis of all the many situations that can be encountered based on the long history of the theory of vortex motion and on many new situations. It gives a renewed insight on the extraordinary richness of vortex dynamics and open the way for new theoretical, observational and experimental advances. This volume is of interest to experts in physical oceanography, meteorology, hydrodynamics, dynamic systems, involved in theoretical, experimental and applied research and lecturers, post-graduate students, and students in these fields.
Download or read book Modeling Atmospheric and Oceanic Flows written by Thomas von Larcher and published by John Wiley & Sons. This book was released on 2014-10-30 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book From Instabilities to Turbulence in Rotating Stratied Ows with Horizontal and Vertical Shear written by Eric Moore Arobone and published by . This book was released on 2014 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two idealized rotating and stratified flows are explored using linear stability analysis and three-dimensional direct numerical simulations. The first problem explores barotropic mean flow containing horizontally-oriented shear flow in the form of a mixing layer. The second problem explores a uniform baroclinic mean flow in the form of a homogeneous density front in thermal wind balance with uniform vertical shear. Both flows are explored using Richardson and Rossby numbers appropriate for submesoscale shear flows, with lateral length scales of roughly 1 to 20 kilometers. The horizontal shear flow results in simultaneous inertial and barotropic instabilities provided the mixing layer vorticity is opposite in sign and substantially greater in magnitude than the Coriolis parameter. When the vorticity of the mixing layer is opposite in sign and similar in magnitude to the Coriolis parameter the barotropic instability is fundamentally altered. The vertical wavenumber associated with this new instability increases by an order of magnitude destabilizing barotropic vortices leading to increased turbulence intensity well outside of the inertially unstable regime. Symmetric instability (fluctuations have no along-front variation and are aligned with isopycnals) has been identified in the literature as a potential route to turbulence at fronts as an alternative to wind-driven boundary layer mixing. Linear analysis and simulations of a uniform baroclinic flow in initial geostrophic balance performed here suggest that the instability responsible for initiating transition to turbulence should be near-symmetric and not exactly symmetric as predicted for asymptotically large time scales. Owing to near-symmetry, the instability fundamentally differs from the purely symmetric instability due to currents crossing surfaces of constant density and tapping the reservoir of potential energy available in the front. The presence of strong vertical shear only intensifies this effect as time increases. A highly-resolved turbulent simulation demonstrates a pathway to turbulence from quiescent flow via near-symmetric currents which succumb to shear-convective instabilities which in turn act to destabilize vorticity fluctuations aligned with the mean vorticity in the base flow. Once these fluctuations are sufficiently strong enough, the flow three--dimensionalizes and rapidly breaks down into turbulence throughout the domain.
Download or read book Fronts Waves and Vortices in Geophysical Flows written by Jan-Bert Flor and published by Springer. This book was released on 2010-06-01 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most well known structures in planetary atmospheres and the Earth’s oceans are jets or fronts interacting with vortices on a wide range of scales. The transition from one state to another, such as in unbalanced or adjustment flows, involves the generation of waves as well as the interaction of coherent structures with these waves. This book presents a fluid mechanics perspective to the dynamics of fronts and vortices and their interaction with waves in geophysical flows. It provides a basic physical background for modeling coherent structures in a geophysical context, and it gives essential information on advanced topics such as spontaneous wave emission and wavemomentum transfer in geophysical flows. Based on a set of lectures by leading specialists, this text is targeted at graduate students, researchers and engineers in geophysics and environmental fluid mechanics.
Download or read book Essential Fluid Dynamics for Scientists written by Jonathan Braithwaite and published by Morgan & Claypool Publishers. This book was released on 2018-01-09 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book is an introduction to the subject of fluid mechanics, essential for students and researchers in many branches of science. It illustrates its fundamental principles with a variety of examples drawn mainly from astrophysics and geophysics as well as from everyday experience. Prior familiarity with basic thermodynamics and vector calculus is assumed.
Download or read book Homogeneous Turbulence Dynamics written by Pierre Sagaut and published by Springer. This book was released on 2018-03-23 with total page 912 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides state-of-the-art results and theories in homogeneous turbulence, including anisotropy and compressibility effects with extension to quantum turbulence, magneto-hydodynamic turbulence and turbulence in non-newtonian fluids. Each chapter is devoted to a given type of interaction (strain, rotation, shear, etc.), and presents and compares experimental data, numerical results, analysis of the Reynolds stress budget equations and advanced multipoint spectral theories. The role of both linear and non-linear mechanisms is emphasized. The link between the statistical properties and the dynamics of coherent structures is also addressed. Despite its restriction to homogeneous turbulence, the book is of interest to all people working in turbulence, since the basic physical mechanisms which are present in all turbulent flows are explained. The reader will find a unified presentation of the results and a clear presentation of existing controversies. Special attention is given to bridge the results obtained in different research communities. Mathematical tools and advanced physical models are detailed in dedicated chapters.
Download or read book Rotating Thermal Flows in Natural and Industrial Processes written by Marcello Lappa and published by John Wiley & Sons. This book was released on 2012-07-25 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rotating Thermal Flows in Natural and Industrial Processes provides the reader with a systematic description of the different types of thermal convection and flow instabilities in rotating systems, as present in materials, crystal growth, thermal engineering, meteorology, oceanography, geophysics and astrophysics. It expressly shows how the isomorphism between small and large scale phenomena becomes beneficial to the definition and ensuing development of an integrated comprehensive framework. This allows the reader to understand and assimilate the underlying, quintessential mechanisms without requiring familiarity with specific literature on the subject. Topics treated in the first part of the book include: Thermogravitational convection in rotating fluids (from laminar to turbulent states); Stably stratified and unstratified shear flows; Barotropic and baroclinic instabilities; Rossby waves and Centrifugally-driven convection; Potential Vorticity, Quasi-Geostrophic Theory and related theorems; The dynamics of interacting vortices, interacting waves and mixed (hybrid) vortex-wave states; Geostrophic Turbulence and planetary patterns. The second part is entirely devoted to phenomena of practical interest, i.e. subjects relevant to the realms of industry and technology, among them: Surface-tension-driven convection in rotating fluids; Differential-rotation-driven (forced) flows; Crystal Growth from the melt of oxide or semiconductor materials; Directional solidification; Rotating Machinery; Flow control by Rotating magnetic fields; Angular Vibrations and Rocking motions; Covering a truly prodigious range of scales, from atmospheric and oceanic processes and fluid motion in "other solar-system bodies", to convection in its myriad manifestations in a variety of applications of technological relevance, this unifying text is an ideal reference for physicists and engineers, as well as an important resource for advanced students taking courses on the physics of fluids, fluid mechanics, thermal, mechanical and materials engineering, environmental phenomena, meteorology and geophysics.
Download or read book Stratified Flows written by E. John List and published by . This book was released on 1990 with total page 1216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Vorticity and Vortex Dynamics written by Jie-Zhi Wu and published by Springer Science & Business Media. This book was released on 2007-04-20 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a comprehensive and intensive monograph for scientists, engineers and applied mathematicians, as well as graduate students in fluid dynamics. It starts with a brief review of fundamentals of fluid dynamics, with an innovative emphasis on the intrinsic orthogonal decomposition of fluid dynamic process, by which one naturally identifies the content and scope of vorticity and vortex dynamics. This is followed by a detailed presentation of vorticity dynamics as the basis of later development. In vortex dynamics part the book deals with the formation, motion, interaction, stability, and breakdown of various vortices. Typical vortex structures are analyzed in laminar, transitional, and turbulent flows, including stratified and rotational fluids. Physical understanding of vertical flow phenomena and mechanisms is the first priority throughout the book. To make the book self-contained, some mathematical background is briefly presented in the main text, but major prerequisites are systematically given in appendices. Material usually not seen in books on vortex dynamics is included, such as geophysical vortex dynamics, aerodynamic vortical flow diagnostics and management.
Download or read book Zonal Jets written by Boris Galperin and published by Cambridge University Press. This book was released on 2019-02-28 with total page 527 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents a comprehensive, multidisciplinary volume on the physics of zonal jets, from the leading experts, for graduate students and researchers.
Download or read book Rotating Fluids in Geophysical and Industrial Applications written by E.J. Hopfinger and published by Springer. This book was released on 2014-05-04 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: The volume presents a comprehensive overview of rotation effects on fluid behavior, emphasizing non-linear processes. The subject is introduced by giving a range of examples of rotating fluids encountered in geophysics and engineering. This is then followed by a discussion of the relevant scales and parameters of rotating flow, and an introduction to geostrophic balance and vorticity concepts. There are few books on rotating fluids and this volume is, therefore, a welcome addition. It is the first volume which contains a unified view of turbulence in rotating fluids, instability and vortex dynamics. Some aspects of wave motions covered here are not found elsewhere.
Download or read book Convection in Rotating Fluids written by B.M. Boubnov and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spatial inhomogeneity of heating of fluids in the gravity field is the cause of all motions in nature: in the atmosphere and the oceans on Earth, in astrophysical and planetary objects. All natural objects rotate and convective motions in rotating fluids are of interest in many geophysical and astrophysical phenomena. In many industrial applications, too (crystal growth, semiconductor manufacturing), heating and rotation are the main mechanisms defining the structure and quality of the material. Depending on the geometry of the systems and the mutual orientation of temperature and gravity field, a variety of phenomena will arise in rotating fluids, such as regular and oscillating waves, intensive solitary vortices and regular vortex grids, interacting vortices and turbulent mixing. In this book the authors elucidate the physical essence of these phenomena, determining and classifying flow regimes in the space of similarity numbers. The theoretical and computational results are presented only when the results help to explain basic qualitative motion characteristics. The book will be of interest to researchers and graduate students in fluid mechanics, meteorology, oceanography and astrophysics, crystallography, heat and mass transfer.
Download or read book Zombie Instability in Rotating Stably Stratified Shear Flows and in Protoplanetary Disks written by Suyang Pei and published by . This book was released on 2014 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most important problems in astrophysics is how angular momentum is transported in protoplanetary disks (PPDs - disks containing gas and dust orbit around newly-forming protostars). Collisional viscosity is believed to be insufficient for angular momentum transport. Therefore, turbulence enhanced transport are proposed. In addition, long-lived coherent vortices are also speculated to exist in PPDs, which could play an important role in completing star formation and building planets. Without instabilities, turbulence and vortices cannot form. In weak magnetized PPDs, magneto-rotational instability (MRI) operates to generate turbulence. However, regions known as ``dead zone", are cool and unionized to have MRI. This has led to intense theoretical and computational search for pure hydrodynamic instabilities. A new hydrodynamic, finite amplitude instability has been discovered in linearly stable, rotating, stably-stratified, shear flows. The instability starts from a new family of critical layers - baroclinic critical layers. These critical layers, which are linear, neutrally stable eigenmodes in stratified shear flows, have singularity in their vertical velocities. Under the effect of rotation, these critical layers produce vortex layers. Vortex layers intensify by drawing energy from the background shear flows, and subsequently roll up to create new vortices, which in turn excite new critical layers. The whole process self-replicates until the whole domain is filled with large-volume, large amplitude vortices. Because this instability can occur in the dead zones of protoplanetary disks we refer it as zombie instability and these new class of vortices that self-replicate as zombie vortices. High resolution numerical simulations show this instability can be triggered by a variety of weak perturbations including small volume compact single vortex, a pair of vortices and noise. The threshold of the instability is determined by the Rossby number or vorticity of the initial perturbations. Energy analysis based on the zonal non-zonal decomposition of the energy shows energy that supplies the instability is extracted from the zonal flows. Vortex is responsible for the energy extraction process. Instability saturates when the all the space are taken by zombie vortices. The separation distance between zombie vortices is approximately the distance from critical layers with lowest stream-wise wave number to the perturbations. The flows at late time are determined only by the background parameters not their initial perturbations. Zombie instability is also discussed in a broader picture to show the dead zones of PPDs are not dead. Our numerical simulation suggest although zombie instability is a finite-amplitude instability, due to the large Reynolds number of the disk flows, it is effectively a linear instability. How zombie instability might lead to sufficient angular momentum transport is also discussed. Finally, we speculate there might not be a laminar Keplerian disks at all. The disk flows are essentially turbulence from the collapsing of gas cloud with possibility turbulent flows filled with zombie vortices. A newly developed semi-analytic method for flows with strong background shear is also presented to be an alternative to widely used shearing sheet method in the astrophysical community. The semi-analytic method is used for simulating internal inertial-gravity waves in rotating, stratified flows with and without shear. The method can also be generalized to systems with linear forcing terms.
Download or read book Fluid Vortices written by Sheldon Green and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 905 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid Vortices is a comprehensive, up-to-date, research-level overview covering all salient flows in which fluid vortices play a significant role. The various chapters have been written by specialists from North America, Europe and Asia, making for unsurpassed depth and breadth of coverage. Topics addressed include fundamental vortex flows (mixing layer vortices, vortex rings, wake vortices, vortex stability, etc.), industrial and environmental vortex flows (aero-propulsion system vortices, vortex-structure interaction, atmospheric vortices, computational methods with vortices, etc.), and multiphase vortex flows (free-surface effects, vortex cavitation, and bubble and particle interactions with vortices). The book can also be recommended as an advanced graduate-level supplementary textbook. The first nine chapters of the book are suitable for a one-term course; chapters 10--19 form the basis for a second one-term course.
Download or read book IUTAM Symposium on Developments in Geophysical Turbulence written by Robert M. Kerr and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: This symposium continues a long tradition for IUGGjIUTAM symposia going back to "Fundamental Problems in Thrbulence and their Relation to Geophysics" Marseille, 1961. The five topics that were emphasized were: turbulence modeling, statistics of small scales and coherent structures, con vective turbulence, stratified turbulence, and historical developments. The objective was to consider the ubiquitous nature of turbulence in a variety of geophysical problems and related flows. Some history of the contribu tions of NCAR and its alumni were discussed, including those of Jackson R Herring, who has been a central figure at NCAR since 1972. To the original topics we added rotation, which appeared in many places. This includes rotating stratified turbulence, rotating convective turbulence, horizontal rotation that appears in flows over terrain and the role of small scale vorticity in many flows. These complicated flows have recently begun to be simulated by several groups from around the world and this meeting provided them with an excellent forum for exchanging results, plus inter actions with those doing more fundamental work on rotating stratified and convective flows. New work on double diffusive convection was given in two presentations. The history of Large Eddy Simulations was presented and several new approaches to this field were given. This meeting also spawned some interesting interactions between observational side and how to inter pret the observations with modeling and simulations around the theme of particle dispersion in these flows.
