Download or read book Computational Techniques for Stratified Shear Flows written by Alexandra VanDine and published by . This book was released on 2019 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work utilizes various computational techniques to study the turbulent mechanisms found in stratified shear flows. Three-dimensional DNS was used to investigate the influence of stratification on turbulence and mixing within a shear layer between two currents. Similarities in the development of secondary instabilities during transition to turbulence and discrepancies in flow evolution are seen between the case of uniform stratification considered here and the two-layer density profile of prior works. Vertical contraction of the shear layer is identified in cases with low Richardson number and determined to be the result of the flattening of Kelvin-Helmholtz billows before the flow becomes fully turbulent. Transition layers with enhanced shear and stratification form at the periphery of the shear layer and are found to support turbulent mixing. In an effort to find a less computationally costly tool than DNS, the Dynamic Smagorinsky, Ducros, and WALE subgrid-scale models were chosen for an LES study of the stratified shear layer. This investigation revealed the Ducros model to the least computationally costly LES option and the most reliable with coarsening grid resolution. A subgrid analysis revealed the LES models to be largely unsuccessful in capturing convective turbulence though the mean flow and turbulent kinetic energy were well-captured. To address the limitations of DNS and LES, a hybrid spatially-evolving DNS model was developed. The wake of a sphere towed in a stratified background was selected for validation. The hybrid model involves extracting planes from a spatially-evolving, body-inclusive simulation and feeding the planes as inflow into a body-exclusive simulation thereby eliminating the need for a highly resolved grid to capture flow near the body. This study revealed that particular attention should be paid to the extraction location, grid resolution, and time step between extractions. Planes must be extracted downstream of the recirculation region behind the body and sufficient grid resolution is required in the body-exclusive simulation to capture small-scale turbulence. Results show the hybrid DNS model to be an effective tool in the study of the stratified turbulent wake. The combination of results presented herein offer computational techniques and cost-saving options for future studies of shear flows.
Download or read book Physical and Computational Modelling of Stratified Shear Flows written by T. N. Stevenson and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Statistical Theories and Computational Approaches to Turbulence written by Y. Kaneda and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 409 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the papers presented at the workshop on Statistical The ories and Computational Approaches to Turbulence: Modern Perspectives and Applications to Global-Scale Flows, held October 10-13, 2001, at Nagoya Uni versity, Nagoya, Japan. Because of recent developments in computational capabilities, the compu tational approach is showing the potential to resolve a much wider range of length and time scales in turbulent physical systems. Nevertheless, even with the largest supercomputers of the foreseeable future, development of adequate modeling techniques for at least some scales of motion will be necessary for practical computations of important problems such as weather forecasting and the prediction and control of global pollution. The more powerful the available machines become, the more demand there will be for precise prediction of the systems. This means that more precise and reliable knowledge of the underlying dynamics will become important, and that more efficient and precise numerical methods best adapted to the new generation of computers will be necessary. The understanding of the nature of unresolved scales then will playa key role in the modeling of turbulent motion. The challenge to turbulence theory here is to elucidate the physics or dynamics of those scales, in particular their sta tistical aspects, and thereby develop models on sound bases to reduce modeling ambiguity. The challenge to the computational method is to develop efficient algorithms suitable for the problems, the machines, and the developed models.
Download or read book Computational Methods and Experimental Measurements written by G.A. Keramidas and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 826 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sponsored by the International Society for Computational Methods in Engineering
Download or read book Computational Methods in Multiphase Flow VIII written by P. Vorobieff and published by WIT Press. This book was released on 2015-04-20 with total page 549 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the latest research in one of the most challenging, yet most universally applicable areas of technology. Multiphase flows are found in all areas of technology, at all length scales and flow regimes, involving compressible or incompressible linear or nonlinear fluids. The range of related problems of interest is vast, including astrophysics, biology, geophysics, atmospheric process, and many areas of engineering. The solution of the equations that describe such complex problems often requires a combination of advanced computational and experimental methods. For example, any models developed must be validated through the application of expensive and difficult experimental techniques. Numerous problems in the area thus remain as yet unsolved, including modelling nonlinear fluids, modelling and tracking interfaces, dealing with multiple length scales, characterising phase structures, and treating drop break-up and coalescence. The papers contained in the book were presented at the eighth in a well established series of biennial conferences that began in 2001. They represent close interaction between numerical modellers and other researchers working to gradually resolve the many outstanding issues in understanding of multiphase flow. The papers in the book cover such topics as: Multiphase Flow Simulation; Bubble and Drop Dynamics; Interface Behaviour; Experimental Measurements; Energy Applications; Compressible Flows; Flow in Porous Media; Turbulent Flow; Image Processing; Heat Transfer; Atomization; Hydromagnetics; Plasma; Fluidised Beds; Cavitation.
Download or read book A Numerical Model of a Stably Stratified Shear Flow with a Turbulent Mixed Layer written by Joanna Marie Brown and published by . This book was released on 2004 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A general method for the linear stability analysis of stratified shear flows written by M.S. DARBY and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Methods in Multiphase Flow V written by Andrea Alberto Mammoli and published by WIT Press. This book was released on 2009 with total page 545 pages. Available in PDF, EPUB and Kindle. Book excerpt: Together with turbulence, multiphase flow remains one of the most challenging areas of computational mechanics and experimental methods and numerous problems remain unsolved to date. Multiphase flows are found in all areas of technology, at all length scales and flow regimes. The fluids involved can be compressible or incompressible, linear or nonlinear. Because of the complexity of the problems, it is often essential to utilize advanced computational and experimental methods to solve the complex equations that describe them. Challenges in these simulations include modelling and tracking interfaces, dealing with multiple length scales, modelling nonlinear fluids, treating drop breakup and coalescence, characterizing phase structures, and many others. Experimental techniques, although expensive and difficult to perform, are essential to validate models. This book contains papers presented at the Fifth International Conference on Computational Methods in Multiphase Flow, which are grouped into the following topics: Multiphase Flow Simulation; Interaction of Gas, Liquids and Solids; Turbulent Flow; Environmental Multiphase Flow; Bubble and Drop Dynamics; Flow in Porous Media; Heat Transfer; Image Processing; Interfacial Behaviour.
Download or read book Environmental Stratified Flows written by Vincenzo Armenio and published by Springer Science & Business Media. This book was released on 2007-03-07 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the theory of stratified flows, from basic concepts to recent developments in environmental fluid mechanics. State-of-the-art numerical techniques suited for stratified flows are given, along with results of recent research in the areas of environmental stratified flows. The book offers a unified view of stratified turbulent flows, from small-scale mixing to large-scale environmental phenomena, including detailed discussion on interaction between turbulence and internal gravity waves.
Download or read book Computational Rheology for Pipeline and Annular Flow written by Wilson C Chin and published by Elsevier. This book was released on 2001-07-30 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Rheology for Pipeline and Annular Flow develops and applies modern analytical and computational finite difference methods for solving flow problems in drilling and production. It also provides valuable insights into flow assurance analysis in subsea pipeline design. Using modeling techniques that simulate the motion of non-Newtonian fluids, e.g., power law, Bingham plastic, and Herschel-Bulkley flows, this book presents proven annular flow methodologies for cuttings transport and stuck pipe analysis based on detailed experimental data obtained from highly deviated and horizontal wells. These methods are applied for highly eccentric borehole geometries to the design of pipeline bundles in subsea applications, where such annular configurations arise in velocity and thermal modeling applications.Also covered extensively are the design and modeling of pipelines having non-circular cross-sections, where deviations from ideal circular geometries arise from plugging due to wax deposition and the presence of hydrates and asphaltenes. As in the case of annular flows, the new algorithms apply to fluids with general rheological description; for example, the methods show very precisely how flow rate and pressure gradient vary nonlinearly in practical problem situations. Provides valuable insights into flow assurance analysis. Contains new algorithms on annular flows and fluids with general rheological descriptions supply solutions to practical problems.
Download or read book Two Numerical Methods for Steady Stratified Shear Flows Over an Obstacle written by William Kingsley Stevens and published by . This book was released on 1979 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Methods in Multiphase Flow III written by Andrea Alberto Mammoli and published by WIT Press. This book was released on 2005 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: A common feature of multiphase flows is that a dispersed or discontinuous phase is being carried by a continuous phase, for example water drops in gas flow, solid particles in water flow, or gas bubbles in liquid flow. The overall behavior of the flow is shaped largely by the interaction between the discontinuous elements--drops, particles, bubbles
Download or read book Stability and Transition in Shear Flows written by Peter J. Schmid and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 561 pages. Available in PDF, EPUB and Kindle. Book excerpt: A detailed look at some of the more modern issues of hydrodynamic stability, including transient growth, eigenvalue spectra, secondary instability. It presents analytical results and numerical simulations, linear and selected nonlinear stability methods. By including classical results as well as recent developments in the field of hydrodynamic stability and transition, the book can be used as a textbook for an introductory, graduate-level course in stability theory or for a special-topics fluids course. It is equally of value as a reference for researchers in the field of hydrodynamic stability theory or with an interest in recent developments in fluid dynamics. Stability theory has seen a rapid development over the past decade, this book includes such new developments as direct numerical simulations of transition to turbulence and linear analysis based on the initial-value problem.
Download or read book Optimal Perturbation Analysis of Stratified Shear Flows written by Matthew Oliver Tearle and published by . This book was released on 2004 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Environmental Stratified Flows written by Roger Grimshaw and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamics of flows in density-stratified fluids has been and remains now an important topic for scientific enquiry. Such flows arise in many contexts, ranging from industrial settings to the oceanic and atmospheric environments. It is the latter topic which is the focus of this book. Both the ocean and atmosphere are characterised 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. The aim of this book is to provide 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, on 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 hand can be regarded as of less importance. This in turn leads to an emphasis on internal waves.
Download or read book A Computational Study of Modal and Non modal Instability in Isothermal and Stratified Parallel Shear Flows written by Helena Vitoshkin and published by . This book was released on 2007 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Methods for Fluid Dynamics written by Joel H. Ferziger and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 431 pages. Available in PDF, EPUB and Kindle. Book excerpt: In its third revised and extended edition the book offers an overview of the techniques used to solve problems in fluid mechanics on computers. The authors describe in detail the most often used techniques. Included are advanced techniques in computational fluid dynamics, such as direct and large-eddy simulation of turbulence. Moreover, a new section deals with grid quality and an extended description of discretization methods has also been included. Common roots and basic principles for many apparently different methods are explained. The book also contains a great deal of practical advice for code developers and users.
