Workshop on Coherent Structure of Turbulent Boundary Layers
Workshop on Coherent Structure of Turbulent Boundary Layers

Author: C. R. Smith

Publisher:

Published: 1978

Total Pages: 528

ISBN-13:

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A discussion of the role of visual and probe measurements in turbulent structure research is given, stressing the constraining limitations of each and the interrelationships of the two methods. A selective history of the use of visual results is discussed in terms of the constraining limitations of the visual methods. Retrospective remarks are presented concerning the Stanford visual data on the inner portions of turbulent boundary layer structure. The final section discusses some general features of what is currently known about the structure of turbulent boundary layers, draws conclusions from this general knowledge, and poses questions that seem currently important in gaining further understanding. The paper stresses overall aspects of the structure problem at the expense of details in an attempt to gain perspective. (Author).

Structure of Turbulence and Drag Reduction
Structure of Turbulence and Drag Reduction

Author: Albert Gyr

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 617

ISBN-13: 3642509711

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In 1976 a similar titled IUTAM Symposium (Structure of Turbulence and Drag Reduction) was held in Washington . However, the progress made during the last thirteen years as weil as the much promising current research desired a second one this year. In Washington drag reduction by additives and by direct manipulation of the walls (compliant walls and heated surfaces) were discussed. In the meantime it became evident that drag reduction also occurs when turbulence is influenced by geometrical means, e.g. by influencing the pressure distribution by the shape of the body (airfoils) or by the introduction of streamwise perturbances on a body (riblets). In the recent years turbulence research has seen increasing attention being focused on the investigation of coherent structures, mainly in Newtonian fluids. We all know that these structures are a significant feature of turbulent flows, playing an important role in the energy balance in such flows. However their place in turbulence theories as weil as the factors influencing their development are still poorly understood. Consequently, the investigation of phenomena in which the properties of coherent structures are alte red provides a promising means of improving our understanding of turbulent flows in general.

River Mechanics
River Mechanics

Author: M.S. Yalin

Publisher: Elsevier

Published: 2015-07-14

Total Pages: 236

ISBN-13: 1483287297

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Understanding the mechanism and behaviour of rivers flowing in alluvium is a most challenging subject. The conditions presented by a natural river are far from simple: the flow varies with location and time, and the granular structure and cohesive properties of the alluvium are rarely homogeneous. River Mechanics addresses this subject and aims to improve the understanding and formulation of the fluvial processes which occur in rivers. Topics covered include the interpretation of turbulence in the light of recent advances in the field, and current thinking on the regime concept.

Turbulence Management and Relaminarisation
Turbulence Management and Relaminarisation

Author: H.W. Liepmann

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 530

ISBN-13: 3642832814

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The last two decades have witnessed an intensifying effort in learning how to manage flow turbulence: it has in fact now become one of the most challenging and prized techno logical goals in fluid dynamics. The goal itself is of course not new. More than a hundred years ago, Reynolds already listed factors conducive to laminar and to turbulent flow (including among them curvature and acceleration). Further more, it is in retrospect clear that there were several early instances ot successful turbulence management. Examples are the reduction in drag achieved with a ring-trip placed on the front of a sphere or the insertion of a splitter-plate behind a circular cylinder; by the early 1950s there were numerous exercises at boundary layer control. Although many of these studies were interesting and suggestive, they led . to no spectacularly successful practical application, and the effort petered out in the late 1950s. The revival of interest in these problems in recent years can be attributed to the emergence of several new factors. First of all, fresh scientific insight into the structure of turbulence, in particular the accumulated evidence for the presence of significant order in turbulent flow, has been seen to point to new methods of managing turbulence. A second major reason has been the growing realisation that the rate at which the world is consuming its reserves of fossil fuels is no longer negligible; the economic value of greater energy effi ciency and lower drag has gone up significantly.

On the Application and Interpretation of Coherent Motion Detectors
On the Application and Interpretation of Coherent Motion Detectors

Author: Charles Paul Gendrich

Publisher:

Published: 1991

Total Pages: 604

ISBN-13:

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Coherent motions are understood to play an important role in enhancing the momentum transport of turbulent wall bounded shear flows, but determining whether or not a coherent motion is present in a given volume of space at a particular time is still a difficult task. Although most detection schemes were developed for use within a specific region above the wall, most are ultimately used throughout the entire boundary layer. Three different probe based algorithms and three different visual detection schemes are applied to combined flow visualization and spanwise vorticity probe data taken in the near wall region and at y/delta of 0.8. Several new performance parameters have been developed, and they are calculated along with most of the commonly used evaluation parameters as functions of detection threshold and Reynolds number or y+. The one to one correspondence between probe based detections and visual detections is also evaluated using two parameters already in common use and a new parameter, P(T, t), which is based on the number of event overlaps as a function of time during an event inner, outer, and mixed variables are used whenever appropriate to scale all results, but only two Reynolds number independent curves are found which describe the outer region response of any detection algorithm as a function of threshold.

Theoretical Approaches to Turbulence
Theoretical Approaches to Turbulence

Author: D.L. Dwoyer

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 377

ISBN-13: 1461210925

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Turbulence is the lIDst natural nDde of fluid lIDtion, and has been the subject of scientific study for all Dst a century. During this period, various ideas and techniques have evolved to nDdel turbulence. Following Saffman, these theoretical approaches can be broadly divided into four overlapping categories -- (1) analytical lIDdelling, (2) physical lIDdelling, (3) phenomenologicalllDdelling, and (4) nurerical lIDdelling. With the purpose of stmtnarizing our =ent understanding of these theoretical approaches to turbulence, recognized leaders (fluid dynamicists, mathematicians and physicists) in the field were invited to participate in a formal workshop during October 10-12, 1984, sponsored by The Institute for CooIputer Applications in Science and Engineering and NASA Langley Research Center. Kraiciman, McCcxnb, Pouquet and Spiegel represented the category of analytical nDdelling, while Landahl and Saffman represented physical lIDdelling. The contributions of Latmder and Spalding were in the category of phenanenological lIDdelling, and those of Ferziger and Reynolds in the area of nurericalllDdelling. Aref, Cholet, Lumley, Moin, Pope and Temam served on the panel discussions. With the care and cooperation of the participants, the workshop achieved its purpose, and we believe that its proceedings published in this vol\. llre has lasting scientific value. The tone of the workshop was set by two introductory talks by Bushnell and ChaImm. Buslmell presented the engineering viewpoint while Chapman reviewed from a historical perspective developments in the study of turbulence. The remaining talks dealt with specific aspects of the theoretical approaches to fluid turbulence.

Flow Control
Flow Control

Author: Mohamed Gad-el-Hak

Publisher: Springer Science & Business Media

Published: 2003-07-01

Total Pages: 533

ISBN-13: 3540696725

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No be certain it can is not based mathematics. knowledge if upon da Vinci, (Leonardo 1452 1519) the humankind. Thinking is one greatest of Joys of Galilei, (Galileo 1564 1642) Now I think is to be the root all hydrodynamics and is at of physical science, second the to none in its mathematics. present beauty of Thomson (William (Lord Kelvin), 1824 1907) The book contains the lecture notes of of the nine instructors at present eight the short Flow Control: Fundamentals and which held course was Practices, in the week 24 28 June and Carg6se, Corsica, France, during 1996, repeated at the of Notre 9 13 1996. University Dame, Indiana, September Following the week in the course a on same was held. Corsica, 5 day workshop topic Selected from the scheduled to 1998 workshop are papers appear early special volume of the International Journal Heat Thermo of Experimental Transfer, and Fluid All Mechanics. three events were Jean Paul dynamics, organized by Bonnet of Universit6 de Andrew Pollard of Univer Poitiers, France, Queen's at and Mohamed Gad el Hak of the of sity Kingston, Canada, University Notre U.S.A.

Turbulence and Related Phenomena
Turbulence and Related Phenomena

Author: Regis Barille

Publisher: BoD – Books on Demand

Published: 2019-04-17

Total Pages: 94

ISBN-13: 1838800174

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This book presents some of the most important results concerning atmospheric turbulence and some of its effects on the propagation of a light beam. Atmospheric turbulence causes fluctuations in both the intensity and the phase of the beam and still must be understood and modelized for applications in photonics or environmental metrology. The future of free-space optical (FSO) communication through atmospheric turbulence channels is especially of interest and research on high bit-rate communications attracts more and more interest as an alternative to radio links because of bandwidth, spectrum, and security issues. Some of the current solutions for improving FSO communications are presented in this book.

Experimental Hydrodynamics for Flow Around Bodies
Experimental Hydrodynamics for Flow Around Bodies

Author: Viktor V. Babenko

Publisher: Academic Press

Published: 2021-01-29

Total Pages: 675

ISBN-13: 0128234482

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Experimental Hydrodynamics for Flow around Bodies explains complex novel experimental methodologies to solve a wide range of important flow problems in industry and research. The book starts by examining the fundamental physical laws necessary for the optimization of techniques for hydro-aeromechanics, heat engineering, and other disciplines related to flow. The reader is then provided with detailed explanations of novel experimental methods, along with the results of physical research. These results are also necessary for the construction of theoretical models that provide improved descriptions for numerous problems in various scientific fields. Frequent discussions, examples of practical applications throughout the text, and foundational, theoretical materials help a range of readers engage and apply these methods to problems in fields including drag reduction, noiseless movement, optimal maneuvering, intense heat transfer, control of separated vortices, wind power, economical energy consumption, and more. - Provides instructions on the set up of innovative experiments for drag reduction that will be of great interest to researchers in aerospace, marine and automotive engineering - Describes, in detail, a variety of novel experiments to investigate boundary layer flow, together with experimental data that can be used with computational models - Assists with bio-inspired hydrodynamic design by providing models of a waving fin mover and investigations of analogs of hydrobiont skin covers