Download or read book Evolution of a Counter rotating Vortex Pair in a Stably Stratified Fluid written by Hideaki Tsutsui and published by . This book was released on 2003 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical and Analytical Studies of Two dimensional Vortex Pair Dynamics in Unstratified and Stratified Environments written by Laura Katherine Brandt and published by . This book was released on 2009 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work investigates fundamental two-dimensional vortex pair dynamics in unstratified and stably stratified environments through numerical and analytical techniques. The study focuses on two main topics: (i) vortex interaction and merging of co-rotating vortex pairs and (ii) internal wave generation by co-rotating and counter-rotating vortex pairs. Two-dimensional vortex merging in a viscous fluid is studied using numerical simulations. Analysis of the ideal case of two equal co-rotating vortices (symmetric pair) identifies the basic underlying physics of vortex merger. Through the interaction of the vorticity gradient and the mutually induced strain rate near the central hyperbolic point, a tilt in vorticity contours is established. This leads to core detrainment and the entrainment of core fluid into the exchange band, which transforms the flow into a single vortex. In the case of the asymmetric (unequal strength) vortex pair, the disparity in the deformation rates between the vortices alters the interaction. A critical value for a strain rate parameter characterizing the establishment of core detrainment is determined. The onset of merging is associated with the achievement of the critical strain by both vortices and a generalized merging criterion is formulated. A classification scheme of the various viscous vortex interactions is developed. Results for the symmetric, horizontally oriented vortex pair in a weakly stratified fluid provide further insight on vortex merging. The effects of weak stratification depend on the ratio of the diffusive time scale to the turnover time, i.e., the Reynolds number. A crossover Reynolds number is found, above which convective merging is accelerated with respect to unstratified flow and below which it is delayed. The generation of internal waves by {\it horizontally} orientated co-rotating and counter-rotating vortex pairs is studied. Linearized inviscid equations are derived that describe the internal wave, vorticity and energy fields. These solutions are compared with nonlinear numerical viscous simulations in moderately and strongly stratified environments. Through evaluation of the energy field, the time at which the flow reaches a steady state for strongly stratified flows is found, along with a characterization of the regimes of strongly and moderately stratified environments.
Download or read book Numerical Simulation of Vortex Dipole Formation and Evolution in Stably Stratified Fluid written by Daniel Neil Mulvaney and published by . This book was released on 2016 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulation of Vortex Dipole Formation and Evolution in Stably Stratified Fluid written by Daniel Mulvaney and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Generation and Evolution of a Viscous Vortex Pair written by Gaurav Gupta and published by . This book was released on 2003 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Interaction Between a Pair of Counter rotating Vortices and a Free Boundary written by Daniel Lewis Marcus and published by . This book was released on 1988 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Vortex Structures in a Stratified Fluid written by Sergey I. Voropayev and published by CRC Press. This book was released on 1994-05-15 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: A fully systematic treatment of the dynamics of vortex structures and their interactions in a viscous density stratified fluid is provided by this book. The various compact vortex structures such as monopoles, dipoles, quadrupoles, as well as more complex ones are considered theoretically from a physical point of view. Another essential feature of the book is the close combination of theoretical analyses with numerous examples of real flows. The book further provides real physical insight and base for postgraduate students specializing in geophysical and applied fluid dynamics. Among the family of vortex structures considered in the book, the most remarkable are the vortex dipoles. These are fundamental elements of the complex chaotic flows associated with the term 'two-dimensional turbulence'. The appearance of these structures in initially chaotic flows is currently of great interest because of a myriad of geophysical applications. Specific examples include the mushroom-like currents discovered from satellite images of the upper ocean. The book is well illustrated with many original photographs (some in colour) and diagrams.
Download or read book The Source and Evolution of Turbulence in Trailing Vortex Pairs written by Christine M. Vogel and published by . This book was released on 1995 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Summary of Flow Modulation and Fluid Structure Interaction Findings written by Wolfgang Schröder and published by Springer Science & Business Media. This book was released on 2010-05-16 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Collaborative Research Center SFB 401: Flow Modulation and Fluid-Structure Interaction at Airplane Wings investigates numerically and experimentally fundamental problems of very high capacity aircraft having large elastic wings. This issue summarizes the findings of the 12-year research program at RWTH Aachen University which was funded by the Deutsche Forschungsgemeinschaft (DFG) from 1997 through 2008. The research program covered the following three main topics of large transport aircraft: (i) Model flow, wakes, and vortices of airplanes in high-lift-configuration, (ii) Numerical tools for large scale adaptive flow simulation based on multiscale analysis and a parametric mapping concept for grid generation, and (iii) Validated computational design tools based on direct aeroelastic simulation with reduced structural models.
Download or read book The Motion of Turbulent Vortex pairs in Homogeneous and Density Stratified Media written by Marshall P. Tulin and published by . This book was released on 1971 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: A theory for the motion of two-dimensional turbulent vortex pairs in homogeneous media has been developed based on separate velocity scaling of the internal and external flow fields involved in the motion and taking into account variations in volume, circulation, momentum, and energy. Based on the results obtained from this theory, a simplified theory is derived to deal with the rising motion of turbulent vortex pairs in stratified media. The theoretical results are compared with systematic experimental observations.
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 AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2006 with total page 1024 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Viscous Flow Induced Near a Wall by Counter rotating Vortex Pairs and Vortex Loops written by Seyham Ersoy and published by . This book was released on 19?? with total page 335 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vortex motion above walls is observed in a variety of physical situations this study the problem of how a viscous flow near a wall responds to the motion of certain vortex motions. Specifically the unsteady boundary layers induced by the motion of two dimensional rectilinear vortex pairs and three dimesional vortex loops in an otherwise stagnant fluid above a plane wall are considered; numerical solutions are obtained for the evolution of the boundary layer flow as it develops under the influence of the moving vortices. All of the vortex flows considered in this study are related to more complex vortex flows observed in a diverse variety of physical situations; many of these situations relate to the observed time-dependent flow in a turbulent boundary layer and are discussed. The boundary layer induced by a pair of counter rotating rectilinear vortices in motion above a plane in an otherwise stagnant fluid is addressed; depending on the assumed sense of rotation the vortices either move toward or recede from the wall. A symmetric situation is considered where both vortices are equidistant from the wall. An symmetric situation is considered where a counter rotating pair approaches the wall at angle of attack. The motion of three-dimensional vortex loops which have a plane of symmetry is considered. A method is developed which allows the computation of the flow velocities on and near the symmetry plane of the loop. The computed results show a variety of complex three dimensional separation phenomena; again the boundary layer solutions ultimately show strong localized growth and are suggestive that a boundary-layer eruption and strong viscous-inviscid interaction will occur.
Download or read book Merging of a Vortex Pair written by Ciro Cerretelli and published by . This book was released on 2003 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Turbulence XII written by Bruno Eckhardt and published by Springer Science & Business Media. This book was released on 2010-03-17 with total page 973 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume comprises the communications presented at the EUROMECH European Turbulence Conference ETC12, held in Marburg in September 2009. The topics covered by the meeting include: Acoustics of turbulent flows, Atmospheric turbulence, Control of turbulent flows, Geophysical and astrophysical turbulence, Instability and transition, Intermittency and scaling, Large eddy simulation and related techniques, Lagrangian aspects, MHD turbulence, Reacting and compressible turbulence, Transport and mixing, Turbulence in multiphase and non-Newtonian flows, Vortex dynamics and structure, formation, Wall bounded flows.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1967 with total page 686 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Vortex Structures in Fluid Dynamic Problems written by Hector Perez-De-Tejada and published by BoD – Books on Demand. This book was released on 2017-03-01 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: The contents of the book cover topics on vortex dynamics in a variety of flow problems and describe observational measurements and their interpretation. The book contains 13 chapters that first include vortices in the earth and planetary sciences related to vortices in the Venus plasma wake and also on tropical cyclones and on rotating shallow water in the earth's atmosphere. Vortices in fluid problems include airplane wake vortices, vorticity evolution in free-shear flows, together with axisymmetric flows with swirl, as well as thermal conductivities in fluid layers. Vortices in relativistic fluids, in magnetic disks, solitons and vortices, and relaxation for point vortices were also examined. Other chapters describe conditions in a vortex bioreactor and in vortex yarn structures.
