Download or read book Mixed Layer Growth in Stratified Fluids written by H. J. S. Fernando and published by . This book was released on 1985 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stratified-fluid turbulence has become of major interest in geophysical fluid mechanics because of its importance in understanding many events related to the atmosphere-ocean system, for example the growth of turbulent mixed layers in the upper ocean or lower atmosphere. Oceanic and atmospheric turbulence is generated in several ways, for example from mean shear, convective heating and cooling, wave-breaking, etc., and the turbulence thus produced interacts with buoyancy forces to cause turbulent mixing. During oceanic wave-breaking, the turbulence is generated within a thin layer (of the thickness of the rm.s. wave amplitude) and is diffused downward toward the htermocline Kitaigorodskii (1979) has suggested that this process could be simulated in the laboratory by an oscillating grid in a density-stratified fluid. An isolated study of a single oceanic turbulence-generating event is an oversimplified attempt to understand the complex events occurring in the real ocean, where many different mechanisms interact; nevertheless, such a study may be of importance in gaining a general understanding of the mechanics of the entrainment process. In this paper, we report some of the features of a detailed study of turbulent entrainment both in linearly-stratified and in two-layer fluids when the turbulence is produces by an oscillating grid. The experimental results are compared with previous theoretical ideas.
Download or read book Turbulent Mixing in Stratified Fluids written by Young-Gyu Park and published by . This book was released on 1993 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: A turbulent mixing experiment was conducted to observe the dynamics and the energetics of layer formation along with the region of layer formation in the Reynolds number (Re) and the overall Richardson number (Rio) space. A salt stratified fluid was mixed uniformly throughout its depth with a vertical rod that moved horizontally at a constant speed. The evolution of density was measured with a conductivity probe. As the instability theory of Phillips (1972) and Posmentier (1977) shows, an initially uniform density profile turns into a series of steps when Rio is larger than a critical value Ric, which forms a stability boundary. For fixed Re, as Rio decreases to Ric, the steps get weaker; the density difference across the interface and the difference of density gradient between layers and interfaces become small. Ric increases as Re increases with a functional relation log Ric ~ Re/900. The steps evolve over time, with small steps forming first, and larger steps appearing later through merging and decay of the interfaces. After some time the interior seems to reach an equilibrium state and the evolution of the interior steps stops. The length scale of the equilibrium step, ls, is a linear function of U /Ni, where U is the speed of the rod and Ni is the buoyancy frequency of the initial profile. The functional relationship is ls = 2.6U / Ni + l. Ocm. For Rio Ric, the mixing efficiency, Rf, monotonically decreases to the end of a run. However, for Rio Ric, the evolution of Rf is closely related to the evolution of the density field. Rf changes rapidly during the initiation of the steps. For Rio” Ric, R1 increases initially, while for Rio e"Ric, Rf ecreases initially. When the interior reaches an equilibrium state, Rf becomes uniform. Posmentier (1977) theorized that when steps reach an equilibrium state, a density flux is independent of the density gradient. The present experiments show a uniform density flux in the layered interior irrespective of the density structure, and this strongly supports the theory of Posmentier. The density flux generated in the bottom boundary mixed layer goes through the interior all the way to the top boundary mixed layer without changing the interior density structure. Thus, turbulence can transport scalar properties further than the characteristic length scale of active eddies without changing a density structure. When the fluid becomes two mixed layers, the relation between Rf and Ril was found for Ril> 1. Here, Ril is the local Richardson number based on the thickness of the interface. R, does decrease as Ril increases, which is the most crucial assumption of the instability theory.
Download or read book The Growth of a Shear Free Mixed Layer in a Lineraly Stratified Fluid written by H. J. S. Fernando and published by . This book was released on 1985 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study is described that deals with the nature of the entrainment zone of a linearly stratified fluid when the turbulence in the mixed layer is generated by an oscillating grid. Measurements include the interfacial-layer thicknesss, frequency, and amplitude of the interfacial waves and the buoyancy flux at the entrainment interface. These measurements were compared with a theor y proposed by Long, part of which (the mixed-layer deepening law) has already been verified by Folse et al. After a certain depth of the mixed layer, the entrainment rate shows an abrupt increase, and this may possibly be caused by wall effects as shown in our previous investigations.
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 A Theory of Mixing in a Stably Stratified Fluid written by Robert R. Long and published by . This book was released on 1977 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: A theory is developed for turbulence in a stably stratified fluid. A growing mixed layer of thickness D appears in the lower portion of the fluid, separated from the non-turbulent fluid above, in which the mean buoyancy gradient is given, by an interfacial layer (IL) of thickness h. When there is stratification, the fluid motion is unaffected by buoyancy forces in the mixed layer. If the upper fluid is of uniform buoyancy, D delta b = v squared may be shown to be constant if we accept the experimental observation that h is proportional to D. In general v may be taken to be a fundamental parameter expressing the stability. The quantity Ri = (v d/k) squared is the most fundamental of the several Richardson numbers that have been introduced in this problem because, with its use, constants of proportionality do not depend on the molecular coefficients of viscosity or diffusion (for high Reynolds number turbulence) or on the geometry of the grid.
Download or read book The Dynamics of a Stratified Mixing Layer with Cross Shear written by Paisan Atsavapranee and published by . This book was released on 1995 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mixing and Dispersion in Stably Stratified Flows written by P. A. Davies and published by Oxford University Press. This book was released on 1999 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stratified flows are important in determining how various atmospheric and environmental processes occur. The book investigates these processes and focuses on the methods by which pollutants are mixed and dispersed in natural and industrial environments.
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 Environmental Fluid Dynamics written by Jorg Imberger and published by Academic Press. This book was released on 2012-09-06 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: A broad cross-section of scientists working in aquatic environments will enjoy this treatment of environmental fluid dynamics, a foundation for elucidating the importance of hydrodynamics and hydrology in the regulation of energy.
Download or read book Turbulence Characteristic in a Stably Stratified Mixing Layer Flow written by Chia-fu Liu and published by . This book was released on 1994 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Recent Awards in Engineering written by and published by . This book was released on 1983 with total page 986 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mixing in a Double diffusive Partially Stratified Fluid written by D. R. Munoz and published by . This book was released on 1986 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this work was to identify the mixing mechanisms and to characterize the entrainment at the interface between a double-diffusive stratification and a mixed layer in the presence of bottom heating, cross flow, or both. Because the scaling and interaction of the entrainment mechanisms were unknown, it was necessry to do the tests at a scale near that of practical engineering applications, thus involving very large Rayleigh number turbulent convection and complex flows produced by submerged turbulent jets in an enclosure. Various values of flow rate, bottom heat flux, density gradient, and mixed layer height were tested. Results of bottom heating alone and cross flow tends to stabilize the system when entrainment rates are on the same order of magnitude as diffusion rates. The data consistently indicated a tendency to an asymptotic value of Ri. Despite great complexity in the flow patterns observed, a generalized entrainment correlation was identified that collapses all data obtained with stratification. Results scaled by this correlation show that a simple Ri power law does not fully represent the system if diffusion is not considered, although the correlation has useful engineering applications.
Download or read book The Ocean Surface written by Y. Toba and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 581 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Small Scale Processes in Geophysical Fluid Flows written by Lakshmi H. Kantha and published by Elsevier. This book was released on 2000-08-07 with total page 921 pages. Available in PDF, EPUB and Kindle. Book excerpt: While ocean waves are the most visible example of oceanic mixing processes, this macroscale mixing process represents but one end of the spectrum of mixing processes operating in the ocean. At the scale of a typical phytoplanktoic diatom or larval fish inhabiting these seas, the most important mixing processes occur on the molecular scale - at the scale of turbulence. Physical-biological interactions at this scale are of paramount importance to the productivity of the seas (fisheries) and the heat balance that controls large scale ocean climate phenomena such as El Niño and tornadoes. This book grew out of the need for a comprehensive treatment of the diverse elements of geophysical fluid flow at the microscale. Kantha and Clayson have arranged a logial exposition of the various mixing processes operating within and between the oceans and its boundaries with the atmosphere and ocean floor. The authors' intent is to develop a volume that would provide a comprehensive treatment of the fundamental elements of ocean mixing so that students, academics, and professional fluid dynamicists and oceanographers can access this essential information from one source. This volume will serve as both a valuable reference tool for mathematically inclined limnologists, oceanographers and fluid modelers. * Simple models of oceanic and atmospheric boundary layers are discussed* Comprehensive and up-to-date review* Useful for graduate level course* Essential for modeling the oceans and the atmosphere* Color Plates
Download or read book Environmental Stratified Flows written by R. Grimshaw and published by Springer Science & Business Media. This book was released on 2002 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamics of flows in density-stratified fluids are an important topic for scientific enquiry. Flows arise in many contexts, ranging from industrial settings to the oceanic and atmospheric environments. Both the ocean and atmosphere are characterized by the basic vertical density stratification, and this feature can affect the dynamics on all scales ranging from the micro-scale to the planetary scale. This volume provides a state-of-the-art account of stratified flows as they are relevant to the ocean and atmosphere, with a primary focus on meso-scale phenomena; that is, phenomena whose time and space scales are such that the density stratification is a dominant effect, so that frictional and diffusive effects on the one hand and the effects of the earth's rotation on the other, can be regarded as of less importance. Environmental Stratified Flows is essential to researchers in the field of oceanography, coastal and marine engineering, and environmental fluid dynamics.
Download or read book The Atmospheric Boundary Layer written by J. R. Garratt and published by Cambridge University Press. This book was released on 1994-04-21 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book gives a comprehensive and lucid account of the science of the atmospheric boundary layer (ABL). There is an emphasis on the application of the ABL to numerical modelling of the climate. The book comprises nine chapters, several appendices (data tables, information sources, physical constants) and an extensive reference list. Chapter 1 serves as an introduction, with chapters 2 and 3 dealing with the development of mean and turbulence equations, and the many scaling laws and theories that are the cornerstone of any serious ABL treatment. Modelling of the ABL is crucially dependent for its realism on the surface boundary conditions, and chapters 4 and 5 deal with aerodynamic and energy considerations, with attention to both dry and wet land surfaces and sea. The structure of the clear-sky, thermally stratified ABL is treated in chapter 6, including the convective and stable cases over homogeneous land, the marine ABL and the internal boundary layer at the coastline. Chapter 7 then extends the discussion to the cloudy ABL. This is seen as particularly relevant, since the extensive stratocumulus regions over the subtropical oceans and stratus regions over the Arctic are now identified as key players in the climate system. Finally, chapters 8 and 9 bring much of the book's material together in a discussion of appropriate ABL and surface parameterization schemes in general circulation models of the atmosphere that are being used for climate simulation.
Download or read book ASME Technical Papers written by and published by . This book was released on 1979 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt:
