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Author : Joseph Mathias Gerardus Kunen
Publisher :
ISBN 13 :
Total Pages : 135 pages
Book Rating : 4.:/5 (219 download)
Download or read book On the Detection of Coherent Structures in Turbulent Flows written by Joseph Mathias Gerardus Kunen and published by . This book was released on 1984 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Joseph M. Kunen
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (115 download)
Download or read book On the detection of coherent structures in turbulent flows written by Joseph M. Kunen and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : O. Métais
Publisher : Springer
ISBN 13 : 9789048140633
Total Pages : 0 pages
Book Rating : 4.1/5 (46 download)
Download or read book Turbulence and Coherent Structures written by O. Métais and published by Springer. This book was released on 2010-12-08 with total page 0 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.
Author : Michael Shats
Publisher : World Scientific
ISBN 13 : 9812566988
Total Pages : 397 pages
Book Rating : 4.8/5 (125 download)
Download or read book Lecture Notes on Turbulence and Coherent Structures in Fluids, Plasmas and Nonlinear Media written by Michael Shats and published by World Scientific. This book was released on 2006 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is based on the lectures delivered at the 19th Canberra International Physics Summer School held at the Australian National University in Canberra (Australia) in January 2006.The problem of turbulence and coherent structures is of key importance in many fields of science and engineering. It is an area which is vigorously researched across a diverse range of disciplines such as theoretical physics, oceanography, atmospheric science, magnetically confined plasma, nonlinear optics, etc. Modern studies in turbulence and coherent structures are based on a variety of theoretical concepts, numerical simulation techniques and experimental methods, which cannot be reviewed effectively by a single expert.The main goal of these lecture notes is to introduce state-of-the-art turbulence research in a variety of approaches (theoretical, numerical simulations and experiments) and applications (fluids, plasmas, geophysics, nonlinear optical media) by several experts. A smooth introduction is presented to readers who are not familiar with the field, while reviewing the most recent advances in the area. This collection of lectures will provide a useful review for both postgraduate students and researchers new to the advancements in this field, as well as specialists seeking to expand their knowledge across different areas of turbulence research.
Author : Sedat Tardu
Publisher : John Wiley & Sons
ISBN 13 : 1848213956
Total Pages : 500 pages
Book Rating : 4.8/5 (482 download)
Download or read book Transport and Coherent Structures in Wall Turbulence written by Sedat Tardu and published by John Wiley & Sons. This book was released on 2014-10-06 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wall bounded turbulent flows are of major importance in industrial and environmental fluid mechanics. The structure of the wall turbulence is intrinsically related to the coherent structures that play a fundamental role in the transport process. The comprehension of their regeneration mechanism is indispensable for the development of efficient strategies in terms of drag control and near wall turbulence management. This book provides an up-to-date overview on the progress made in this specific area in recent years.
Author : Duncan Burnette Bryant
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (747 download)
Download or read book Coherent Structures in Turbulent Flows written by Duncan Burnette Bryant and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents the turbulence of multiphase plumes and tidal vortices by studying and quantifying coherent structures that affect the dynamics of the flow. The measurements presented in this dissertation were taken using particle image velocimetry (PIV). After preprocessing the images and conducting the PIV analysis to get the final velocity fields, the local swirl strength was used to identify coherent structures (vortices) in the flow. This dissertation used the identified vortices to quantify the turbulent properties of the flows. The mean and turbulent properties of bubble plumes are found to be self-similar within the measured air flow rates when appropriately nondimensionalized. The timeaveraged velocity profile was shown to have a Gaussian distribution when nondimensionalized by the centerline velocity and plume radius. The bubble plumes were found to have the most energetic vortices along the plume edge and a modulated turbulent energy spectrum with a slope in the inertial subrange from -7/6 instead of the classical -5/3. The mean and turbulent properties of an inertial particle plume are presented, revealing the time-averaged velocity and vorticity profiles to be self-similar for all cases when nondimesionalized by the centerline velocity and plume radius. The average vortex properties were not self-similar for all flow cases with the largest two particles sizes being self-similar and the smallest particle vortex properties being similar to bubble plume data. Despite the difference in vortex properties, the turbulent energy spectra in inertial particle plumes followed the same modulation as the bubble plumes. PIV experiments from the tidal starting-jet vortices detail the influence of a finite channel length using identified vortice. The results show the trajectory and development of the tidal starting-jet vortices to be changed by a region of vorticity that develops inside the channel and is expelled as a vortex during the ebb tide. This expelled lateral boundary layer vortex is shown to move the starting-jet vortex away from the tidal jet shear layer thus reducing the input vorticity. When the expelled boundary layer vortex strength is 1/5 the starting-jet vortex the system dynamics change resulting in a deviation in the starting-jet vortices' trajectory. This dissertation successfully uses the local swirl strength to quantify the turbulence of multiphase plumes and tidal starting-jet vortices. Using these results, engineers will be able to better predict the efficiency of CO2 ocean sequestration and tidal flushing. Furthermore, the techniques of quantifying coherent structures developed in this dissertation can be applied to a multitude of turbulent flows.
Author : Tardu Sedat
Publisher : Wiley-ISTE
ISBN 13 : 9781848215061
Total Pages : 256 pages
Book Rating : 4.2/5 (15 download)
Download or read book Coherent Structures in Parietal Turbulent Flows written by Tardu Sedat and published by Wiley-ISTE. This book was released on 2015-11-09 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: The wall is a source of many complexities, including turbulence modeling, and thus requires a thorough understanding of all the physics involved. Coherent Structures in Parietal Turbulent Flows provides scientists, researchers, and engineers with all the necessary information on the physical analysis, measurement, and calculation of these flows. Taking into account the latest developments in the field, the author discusses the fundamentals of turbulence, phenomenology, and closures of spectral behavior, the effect of the Reynolds number on parietal turbulence characteristics, and transport of vorticity.
Author : Noushin Amini
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (812 download)
Download or read book Turbulent Flow Analysis and Coherent Structure Identification in Experimental Models with Complex Geometries written by Noushin Amini and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent flows and coherent structures emerging within turbulent flow fields have been extensively studied for the past few decades and a wide variety of experimental and numerical techniques have been developed for measurement and analysis of turbulent flows. The complex nature of turbulence requires methods that can accurately estimate its highly chaotic spatial and temporal behavior. Some of the classical cases of turbulent flows with simpler geometries have been well characterized by means of the existing experimental techniques and numerical models. Nevertheless, since most turbulent fields are of complex geometries; there is an increasing interest in the study of turbulent flows through models with more complicated geometries. In this dissertation, characteristics of turbulent flows through two different facilities with complex geometries are studied applying two different experimental methods. The first study involves the investigation of turbulent impinging jets through a staggered array of rods with or without crossflow. Such flows are crucial in various engineering disciplines. This experiment aimed at modeling the coolant flow behavior and mixing phenomena within the lower plenum of a Very High Temperature Reactor (VHTR). Dynamic Particle Image Velocimetry (PIV) and Matched Index of Refraction (MIR) techniques were applied to acquire the turbulent velocity fields within the model. Some key flow features that may significantly enhance the flow mixing within the test section or actively affect some of the structural components were identified in the velocity fields. The evolution of coherent structures within the flow field is further investigated using a Snapshot Proper Orthogonal Decomposition (POD) technique. Furthermore, a comparative POD method is proposed and successfully implemented for identification of the smaller but highly influential coherent structures which may not be captured in the full-field POD analysis. The second experimental study portrays the coolant flow through the core of an annular pebble bed VHTR. The complex geometry of the core and the highly turbulent nature of the coolant flow passing through the gaps of fuel pebbles make this case quite challenging. In this experiment, a high frequency Hot Wire Anemometry (HWA) system is applied for velocity measurements and investigation of the bypass flow phenomena within the near wall gaps of the core. The velocity profiles within the gaps verify the presence of an area of increased velocity close to the outer reflector wall; however, the characteristics of the coolant flow profile is highly dependent on the gap geometry and to a less extent on the Reynolds number of the flow. The time histories of the velocity are further analyzed using a Power Spectra Density (PSD) technique to acquire information about the energy content and energy transfer between eddies of different sizes at each point within the gaps.
Author : Marco Atzori
Publisher :
ISBN 13 : 9789178739172
Total Pages : pages
Book Rating : 4.7/5 (391 download)
Download or read book Coherent Structures and Control in Wall-bounded Turbulent Flows written by Marco Atzori and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 52 pages
Book Rating : 4.:/5 (317 download)
Download or read book On the Structure of Wall-bounded Turbulent Flows written by and published by . This book was released on 1983 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Zeinab Hallol
Publisher : Cuvillier
ISBN 13 : 9783736975019
Total Pages : 146 pages
Book Rating : 4.9/5 (75 download)
Download or read book Behaviour of Energetic Coherent Structures in Turbulent Pipe Flow at High Reynolds Number written by Zeinab Hallol and published by Cuvillier. This book was released on 2021-10-26 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a new applied temporal-spatial analysis using time-resolved PIV measurements to investigate coherent structures' co-exist towards pipe axis in fully developed turbulent pipe flow at high Reynolds numbers. The new method facilitates the detection of coherent structures directly through the new streamwise fluctuating velocity field plots. The detection was done without involving the common usable Taylor hypothesis compared to the recognised spectral analysis. For streamwise (u) and wall-normal (v) velocity components, this methodology identifies the shear layer signature created by the encounters of bursting events caused due to the intensive presence of coherent structures and their interaction in the near-wall region. Nevertheless, spectra and co-spectra, as well as proper orthogonal decomposition (POD) analyses, are also applied in this study to identify the contribution of both large (LSMs) and very-large-scale motions (VLSMs) to turbulent kinetic energy and Reynolds shear stress. The spectral analysis utilises high-speed PIV measurements to revisit other earlier studies done via a single hot-wire anemometer. In the present study, hot-wire measurements were conducted at a very high Reynolds number range exceeding one million equivalent to Re_tau= 19 000 with high spatial resolution. The obtained results indicate the dominance of VLSMs in the logarithmic and outer layers. However, the outputs are deduced from their higher contribution to total energy production in streamwise and wall-normal directions at high Reynolds numbers. Furthermore, new observation explored from the temporal-spatial plots stated that VLSMs could be created from the alignment of LSMs.
Author :
Publisher :
ISBN 13 :
Total Pages : 17 pages
Book Rating : 4.:/5 (79 download)
Download or read book עמק חברון written by and published by . This book was released on 1969 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Hassan M. Nagib
Publisher :
ISBN 13 :
Total Pages : 16 pages
Book Rating : 4.3/5 (91 download)
Download or read book Management and Control of Unsteady and Turbulent Flows written by Hassan M. Nagib and published by . This book was released on 1988 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721243327
Total Pages : 38 pages
Book Rating : 4.2/5 (433 download)
Download or read book Detection, Tracking and Analysis of Turbulent Spots and Other Coherent Structures in Unsteady Transition written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-16 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition on turbine blades is an important factor in the determination of eventual flow separation and engine performance. The phenomenon is strongly affected by unsteady flow conditions (wake passing). It is likely that some physics of unsteadiness should be included in advanced models, but it is unclear which properties would best embody this information. In this paper, we use a GEAE experimental database in unsteady transition to test some tools of spot identification, tracking and characterization. In this preliminary study, we identify some parameters that appear to be insensitive to wake passing effects, such as convection speed, and others more likely to require unsteady modeling. The main findings are that wavelet duration can be used as a measure of spot size, and that spot energy density is most closely correlated to the wake passing. The energy density is also correlated to spot size, but spot size appears unrelated to the phase angle. Recommendations are made for further study. Lewalle, Jacques and Ashpis, David (Technical Monitor) Glenn Research Center NASA/CR-2000-210694, E-12622, NAS 1.26:210694
Author : Hiroji Nakagawa
Publisher : Routledge
ISBN 13 : 1351406612
Total Pages : 293 pages
Book Rating : 4.3/5 (514 download)
Download or read book Turbulence in Open Channel Flows written by Hiroji Nakagawa and published by Routledge. This book was released on 2017-10-02 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of open channel turbulence, focusing especially on certain features stemming from the presence of the free surface and the bed of a river. Part one presents the statistical theory of turbulence; Part two addresses the coherent structures in open-channel flows and boundary layers.
Author :
Publisher :
ISBN 13 :
Total Pages : 26 pages
Book Rating : 4.:/5 (317 download)
Download or read book Detection, Tracking and Analysis of Turbulent Spots and Other Coherent Structures in Unsteady Transition written by and published by . This book was released on 2000 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : J.P. Bonnet
Publisher : CISM International Centre for Mechanical Sciences
ISBN 13 :
Total Pages : 376 pages
Book Rating : 4.F/5 ( download)
Download or read book Eddy Structure Identification written by J.P. Bonnet and published by CISM International Centre for Mechanical Sciences. This book was released on 1996-06-04 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a unique opportunity to present in a single volume information that is needed for both experimentalists, theoreticians and computationalists for the detection, analysis, prediction and control of eddy structures in turbulent shear flows. Major identification techniques of Eddy Structures in Turbulent Shear Flows are presented together with applications to vortex dynamics, turbulence management and flow control, for experimental and numerical applications with new prediction methods: Eduction Schemes, Proper Orthogonal Decomposition, Stochastic Estimation, Pattern Recognition Analysis, Wavelet Transform. Illustrations of the use of the different methods are given.
