Download or read book Numerical Simulations of Internal Waves Around Bodies in Density Stratified Fluids written by Lap Yan Pao and published by . This book was released on 1990 with total page 301 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulations of Internal Waves in Stratified Fluids written by Andy K. O. Law and published by . This book was released on 1999 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nonlinear Internal Waves in Lakes written by Kolumban Hutter and published by Springer Science & Business Media. This book was released on 2011-11-25 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Internal wave dynamics in lakes (and oceans) is an important physical component of geophysical fluid mechanics of ‘quiescent’ water bodies of the Globe. The formation of internal waves requires seasonal stratification of the water bodies and generation by (primarily) wind forces. Because they propagate in basins of variable depth, a generated wave field often experiences transformation from large basin-wide scales to smaller scales. As long as this fission is hydrodynamically stable, nothing dramatic will happen. However, if vertical density gradients and shearing of the horizontal currents in the metalimnion combine to a Richardson number sufficiently small (
Download or read book Internal Waves in the Ocean written by Marek Stastna and published by Springer Nature. This book was released on 2022-06-16 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph provides a concise overview of nonlinear internal wave theory. It serves as a self-contained reference for both students of mathematics as well as scientific professionals by presenting the material in two parts, isolating the narrative analysis from the mathematical detail. This unique format allows the text to remain accessible to oceanographers and researchers outside of mathematics by presenting a range of relevant theories on their own terms. Conversely, it enables applied mathematicians to understand how the conversation between mathematics and sciences proceeds in a field that has developed through a combination of the two. In addition, the text is supplemented by hands-on Matlab software, as the book incorporates a collection of working codes that enable readers to reproduce all theoretical figures in the text, with modification potential to fit a range of applications including a number of mini-projects outlined throughout the text.
Download or read book Laboratory experiments and numerical simulations of inertial waves in a rotating spherical shell written by Sandy Dahley and published by Cuvillier Verlag. This book was released on 2016-02-01 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geo- und astrophysikalisch motivierte Strömungen, wie sie in der Atmosphäre, in den Ozeanen oder im Inneren von Planeten auftreten, lassen sich in rotierenden Experimenten mit homogenen Fluiden untersuchen. In dieser Arbeit werden Untersuchungen zu Trägheitswellen und Wellenattraktoren in einer Kugelschale und einem rechteckigen Tank gezeigt. Viele geophysikalische Anwendungen mit planetaren Skalen motivieren den Einsatz von sphärischen Geometrien. Mit dem Kugelspaltexperiment, bestehend aus zwei rotierenden konzentrisch angeordneten Kugelschalen, werden die Anregung und Ausbildung verschiedener Wellenphänomene sowie der internen Grenzschichten untersucht. Durch eine Modulation der Rotationsgeschwindigkeit an der Innenkugel in Form einer Sinuskurve werden Wellen erzeugt, die an den gekrümmten Rändern des Modells mehrfach reflektiert werden und somit bestimmten Bahnen folgen. Für den Vergleich mit numerischen Untersuchungen werden unterschiedliche Visualisierungen und Messtechniken spezifiziert. Die numerische Simulation erlaubt dabei die Untersuchung in Parameterbereichen mit Instabilitäten, die für die experimentelle Untersuchung schwer zugänglich sind.
Download or read book A Numerical Study of Upstream Blocking and Internal Waves in a Density Stratified Fluid written by Chang-Yang Li and published by . This book was released on 1978 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Internal Gravity Waves written by Bruce Sutherland and published by Cambridge University Press. This book was released on 2010-09-02 with total page 395 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first comprehensive treatment of the theory for small and large amplitude internal gravity waves, with illustrative examples and exercises.
Download or read book Stratified Flows written by Chia-Shun Yih and published by Elsevier. This book was released on 2012-12-02 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stratified Flows is the second edition of the book Dynamics of Nonhomogenous Fluids. This book discusses the flow of a fluid of variable density or entropy in a gravitational field. In this edition, corrections have been made; unnecessary parts have been omitted; and new sections as well as notes on results related to the subject have been added. This book includes a general discussion of the effects of density or entropy and the structure of stratified flows; waves of small amplitude; the Eigenvalue problem; dependence of phase velocity on wavelength; wave motion; steady flows of finite amplitude; and types of solutions for steady flows. This edition also covers other topics such as hydrodynamic stability; flows in porous media; and the analogy between gravitational and electromagnetic forces. This text is recommended for those in the field of physics who would like to be familiarized with stratified flows and its related concepts.
Download or read book Dynamics of Stratified Flow Past a Sphere written by Anikesh Pal and published by . This book was released on 2016 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wakes of bluff bodies in a stratified environment are common in oceanic and atmospheric flows. Some examples are marine swimmers, underwater submersibles and flow over mountains and islands. The first part of the research in stratified wakes concerns temporal/spatial simulations of turbulent self-propelled/towed wakes without including a body. Direct numerical simulations are performed to contrast the influence of the mean velocity profile with that of the initial turbulence on the subsequent evolution of velocity and density fluctuations in a stratified self-propelled wake. It is also verified that results of temporal simulations matches with that of the spatial simulations when the initial near-wake condition of the temporal approximation is chosen to match the inflow of the spatially evolving model. Typically, the wake of a body develops in the presence of external fluctuations, motivating a study of wake evolution under the influence of various intensities of external turbulence. The stratified wake was found to decay substantially faster than its unstratified counterpart for same intensity of the external turbulence. Theoretical arguments and additional simulations were performed to show that the level of external turbulence relative to wake turbulence is a key governing parameter in both stratified and unstratified backgrounds. The second part of this research focuses on flow past a sphere in a stratified fluid at a sub-critical Reynolds number of 3,700 and for a range of Froude numbers U/ND \in [0.025,1]. The conservation equations are solved in a cylindrical coordinate system and an immersed boundary method is employed to represent the sphere. The prime objective of this investigation is to understand the statistical response of the near, intermediate and far wake of a sphere at sub-critical Re under the influence of buoyancy. It is observed that buoyancy leads to the inhibition of vertical motion resulting in faster decay of r.m.s. velocity in the vertical direction as compared to the horizontal r.m.s. velocity, collapse of the wake, propagation of internal gravity waves and the organization of the primarily horizontal flow into coherent vortical structures. Unprecedented with respect to previous studies, the time averaged turbulent kinetic energy budget is closed for the unstratified and stratified cases. A novel finding of this research is the regeneration of turbulent fluctuations in the near wake when the stratification increases beyond a critical level (Fr decreases beyond a critical value) which is in contrast to the previous results at lower Re that suggest monotone suppression of turbulence with increasing stratification. Vorticity evolution, energy spectra and the turbulence energy equation explain turbulence regeneration. Another objective of this study is to quantify the distinction between the body and turbulence generated internal waves, in terms of the amplitude, frequency, potential energy distribution and propagation angles. With a decrease in Fr, the body generation mechanism become stronger and waves exhibit upstream propagation.
Download or read book Interaction of Waves in a Two layer Density Stratified Fluid written by Mohammad-Reza Alam and published by . This book was released on 2008 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the first part of this thesis, the mechanisms of nonlinear resonant interaction of surface-interfacial waves with a rippled bottom in a two-layer density stratified fluid in two dimensions is investigated via perturbation analyses and direct simulation. Three classes of Bragg resonances are found to exist if the nonlinear interactions up to third order in the wave/ripple steepness are considered. At second order, class I Bragg resonance occurs involving two surface and/or internal waves and one bottom ripple component. At third order, class II and III Bragg resonances occur involving resonant interactions of four wave/ripple components. A powerful high-order spectral (HOS) method for nonlinear gravity wave dynamics in a homogeneous fluid is extended to the case of a two-layer fluid over non-uniform bottom. The method is capable of capturing the nonlinear interactions among large number of surface/interfacial wave mode and bottom ripple components up to an arbitrary high order. As an illustration of the usefulness of the numerical method a somewhat complicated problem involving many wave/bottom components is considered and it is shown that the ensuing multiple (near) resonant interactions result in the generation of multiple new transmitted/reflected waves that fill a broad wavenumber band eventually leading to loss of order and chaotic motion. In the second part of this thesis, Resonance between waves of an oscillating/translating disturbance in two-layer density stratified fluids is studied. Waves in homogeneous fluid are known to be non-resonant at the second order. Many seas and oceans, however, are weakly stratified. Here it is shown that in the presence of stratification triad resonance between ship-generated waves can occur. For the more general problem and as an independent validation, the HOS is extended to consider the effect of the current and an oscillating submerged singularity. Direct simulation results compare well with analytical predictions in the near- and far-fields and offer a powerful tool for practical problems with general time-dependent motions/interactions of one or more bodies.
Download or read book Numerical and analytical study of internal waves in stratified fluids written by Ren Liu and published by . This book was released on 1989 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulations of Internal Solitary and Solitary like Waves written by Chengzhu Xu and published by . This book was released on 2019 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Internal solitary and solitary-like waves (ISWs) are commonly observed in stably stratified fluids such as the Earth's atmosphere and oceans. As these waves interact with other physical processes and/or move through a varying background environment, they may change their form and possibly become unstable. In this thesis, we study ISWs using high-resolution direct numerical simulations and address three major topics: the interaction of ISWs with short waves, the onset of shear instability in ISWs, and the dynamics of ISWs in a shear background current induced by basin-scale standing internal waves. The first topic examines the behavior of short internal waves as they propagate through large-amplitude ISWs. A key finding is that for waves that are short in comparison to the ISW width, the interaction leads to an almost complete destruction of the short waves, but that longer waves are able to maintain their structure after the interaction. The destruction of short waves occurs primarily due to the velocity shear induced by the ISW, which alters the vertical structure of the short waves so that significant wave activity is found only on the upstream side of the ISW crest (i.e. the deformed pycnocline). These results suggest that through the interaction with waves of relatively smaller length scale, ISWs can provide a means to decrease the power observed in the short-wave band in the coastal ocean. The second topic focuses on the onset and growth of shear instability in ISWs, which is particularly important for the diapycnal mixing in open waters. The complexity of instability onset in ISWs is due to the finite length and the non-parallel structure of the wave-induced high-shear region. We examine large-amplitude ISWs with a flat crest and show that, depending on the ratio of the length of high shear region and the width of the wave, there are cases in which instability can occur spontaneously, cases in which its onset is Reynolds number dependent, and cases in which instability does not occur spontaneously but must be triggered by small, but finite amplitude noise. The amplitude of the noise has a crucial influence on the instability growth, regardless of its spatial structure. In the final topic we study the effect of a shear background current on the dynamics of ISWs by investigating the interaction of ISWs with basin-scale standing internal waves. The ISWs are generated using a lock-release mechanism, while the seiches are created using a tilted tank suddenly returned to the upright position, both of which are readily realizable in a laboratory. In most cases, the wave forms of ISWs in the simulations match those described by the fully nonlinear theory, implying that in laboratory experiments ISWs propagating in a shear background current can be generated in a similar manner. In some circumstances, however, the presence of a shear background current prevents the formation of ISWs, but enables the formation of a finite amplitude dispersive wave train, even when the pycnocline center is not close to the mid-depth.
Download or read book Viscous internal waves in density stratified fluids written by Uri Rudi Klement and published by . This book was released on 1975 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Parametric Instabilities of Internal Gravity Waves in a Density stratified Fluid written by Yuanxun Bill Bao and published by . This book was released on 2012 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: The parametric instability of a finite-amplitude, internal gravity wave is a widely studied process in atmospheric and oceanic fluid dynamics, and has been extensively investigated through experiments and direct numerical simulations. The mathematical approach of the Floquet-Fourier method leads to a linear algebraic computation of Floquet exponents (stability eigenvalues) as a function of disturbance wavenumbers. The number of numerical eigenvalues is determined by the truncation of the Fourier series in the Floquet solution of the linearized Boussinesq equations. Yet, the physical linear dispersion relation for the frequency eigenvalues is only a double-valued function of wavenumbers. We investigate this ambiguity in the eigenvalue count through the development of resonant-mode perturbation analyses that identify the physically relevant instabilities. Our choice of Floquet exponents is interpreted as branches of a Riemann surface from the complex analysis of Floquet spectral theory.
Download or read book Turbulence and Coherent Structures written by O. Métais and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last 25 years, one of the most striking advances in Fluid Mecha nics was certainly the discovery of coherent structures in turbulence: lab oratory experiments and numerical simulations have shown that most turbulent flows exhibit both spatially-organized large-scale structures and disorganized motions, generally at smaller scales. The develop ment of new measurement and visualization techniques have allowed a more precise characterization and investigation of these structures in the laboratory. Thanks to the unprecedented increase of computer power and to the development of efficient interactive three-dimensional colour graphics, computational fluid dynamicists can explore the still myste rious world of turbulence. However, many problems remain unsolved concerning the origin of these structures, their dynamics, and their in teraction with the disorganized motions. In this book will be found the latest results of experimentalists, theoreticians and numerical modellers interested in these topics. These coherent structures may appear on airplane wings or slender bodies, mixing layers, jets, wakes or boundary-layers. In free-shear flows and in boundary layers, the results presented here highlight the intense three-dimensional character of the vortices. The two-dimensional large scale eddies are very sensitive to three-dimensional perturbations, whose amplification leads to the formation of three-dimensional coherent vorti cal structures, such as streamwise, hairpin or horseshoe vortex filaments. This book focuses on modern aspects of turbulence study. Relations between turbulence theory and optimal control theory in mathematics are discussed. This may have important applications with regard to, e. g. , numerical weather forecasting.
Download or read book Ocean Mixing written by Michael Meredith and published by Elsevier. This book was released on 2021-09-16 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ocean Mixing: Drivers, Mechanisms and Impacts presents a broad panorama of one of the most rapidly-developing areas of marine science. It highlights the state-of-the-art concerning knowledge of the causes of ocean mixing, and a perspective on the implications for ocean circulation, climate, biogeochemistry and the marine ecosystem. This edited volume places a particular emphasis on elucidating the key future questions relating to ocean mixing, and emerging ideas and activities to address them, including innovative technology developments and advances in methodology. Ocean Mixing is a key reference for those entering the field, and for those seeking a comprehensive overview of how the key current issues are being addressed and what the priorities for future research are. Each chapter is written by established leaders in ocean mixing research; the volume is thus suitable for those seeking specific detailed information on sub-topics, as well as those seeking a broad synopsis of current understanding. It provides useful ammunition for those pursuing funding for specific future research campaigns, by being an authoritative source concerning key scientific goals in the short, medium and long term. Additionally, the chapters contain bespoke and informative graphics that can be used in teaching and science communication to convey the complex concepts and phenomena in easily accessible ways. - Presents a coherent overview of the state-of-the-art research concerning ocean mixing - Provides an in-depth discussion of how ocean mixing impacts all scales of the planetary system - Includes elucidation of the grand challenges in ocean mixing, and how they might be addressed
Download or read book Numerical Simulations of Internal Waves Generated by Flow Over a Ridge written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: QIAN, HUI. Numerical Simulations of Internal Waves Generated by Flow over a Ridge. (Under the direction of Dr. Ping-Tung Shaw). A three-dimensional nonhydrostatic numerical model is used to study the generation of internal wave energy by barotropic tidal flow over a steep ridge. Numerical experiments are carried out over ridges of three different heights in an ocean with strong stratification at shallow depths. The topographic width, stratification, and amplitude of the barotropic tide are varied to examine the dependence of the normalized energy flux on the slope parameter, the ratio of the ridge slope to that of the wave beam. Over a tall ridge reaching the strongly stratified depths of the water column, the non-dimensional energy flux increases with the slope parameter and becomes constant when the slope parameter exceeds a critical value. For a small ridge confined at weakly stratified depths, the non-dimensional energy flux reaches a maximum with increase in the slope parameter but decreases with further increase in the slope parameter. The two regimes of dependence on the slope parameter can be described in terms of a local Froude number. The results show that internal wave generation is most efficient when the ridge is steep and the ridge top reaches the strongly stratified upper ocean. Comparison between the parameterization scheme and the estimated energy flux at several locations in the ocean shows reasonable agreement. The non-dimensional relation provides a way to estimate the baroclinic energy flux using topographic scales, stratification, and strength of the barotropic tides in the ocean.
