Experimental Investigation of coherent structures in turbulent boundary layers
Author: Candace Elaine Wark
Publisher:
Published: 1989
Total Pages: 588
ISBN-13:
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Author: Candace Elaine Wark
Publisher:
Published: 1989
Total Pages: 588
ISBN-13:
DOWNLOAD EBOOKAuthor: D. E. Abbott
Publisher:
Published: 1980
Total Pages: 17
ISBN-13:
DOWNLOAD EBOOKThis project combines both experimental video flow visualization studies and theoretical investigations of a series of phenomenological and theoretical models based upon the three-dimensional details of convected, coherent structural elements of a turbulent flow as it interacts with a solid surface. The progress over the past year has led to the experimental consideration of range of sub-problems including high Reynolds Number (4,000,000) turbulent flows, the effect of surface modification on low-speed streak formation, and the effect of vortex loop interaction with a solid boundary. To augment the visualization pictures, a computerized video-digitizing system has been developed. Preliminary results show tremendous promise for obtaining quantitative data from flow visualization pictures. The specific thrust of the theoretical studies has been focussed on three areas: (1) how two- and three-dimensional vortex structures interact with wall boundary layers, (2) the development of a new type of prediction method for two-dimensional turbulent boundary-layer flows, and (3) improvement in numerical techniques for solving parabolic, boundary-layer equations. (Author).
Author: C. R. Smith
Publisher:
Published: 1982
Total Pages: 32
ISBN-13:
DOWNLOAD EBOOKThis program combines both experimental flow visualization studies with analytical investigations of a series of phenomenological and theoretical models based upon three-dimensional, vortical flow structures developing and interacting in proximity to a solid surface. The experimental program considered a range of sub-problems including the effect of surface modifications on low-speed streak formation and drag, and the effect of vortex loop inter-action with a solid boundary. To augment visual studies, a computerized interface with the video system has been developed which allows quantitative data to be obtained from flow visualization pictures. The specific thrust of the theoretical studies has been focussed on three areas: (1) how two and three-dimensional vortex structures interact with wall boundary layers; (2) the development of a new type of prediction method for two-dimensional turbulent boundary-layer flows; and (3) improvement in numerical techniques for solving parabolic, boundary-layer equations.
Author: Stephen Jay Kline
Publisher:
Published: 1991
Total Pages: 60
ISBN-13:
DOWNLOAD EBOOKAuthor: O. Métais
Publisher: Springer Science & Business Media
Published: 2013-03-09
Total Pages: 612
ISBN-13: 9401579040
DOWNLOAD EBOOKIn 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: William Thomas Hambleton
Publisher:
Published: 2007
Total Pages: 346
ISBN-13:
DOWNLOAD EBOOKAuthor: Siew-Mun Ha
Publisher:
Published: 1993
Total Pages: 556
ISBN-13:
DOWNLOAD EBOOKAuthor: S. J. Kline
Publisher:
Published: 1960
Total Pages: 70
ISBN-13:
DOWNLOAD EBOOKAuthor: Gazi Hasanuzzaman
Publisher: Cuvillier Verlag
Published: 2022-01-18
Total Pages: 180
ISBN-13: 3736965583
DOWNLOAD EBOOKExperimental investigation in turbulent boundary layer flows represents one of the canonical geometries of wall bounded shear flows. Utmost relevance of such experiments, however, is applied in the engineering applications in aerospace and marine industries. In particular, continuous effort is being imparted to explore the underlying physics of the flow in order to develop models for numerical tools and to achieve flow control. Flow control experiments have been widely investigated since 1930’s. Several flow control technique has been explored and have shown potential benefit. But the choice of control technique depends largely on the boundary condition and the type of application. Hence, friction drag of subsonic transport aircraft is intended to be reduced within the scope of this Ph. D. topic. Therefore, application of active control method such as microblowing effect in the incompressible, zero pressure gradient turbulent boundary layer was investigated. A series of experiments have been performed in two different wind tunnel facilities. Wind tunnel from Department of Aerodynamics and Fluid Mechanics (LAS) was used for the measurements for moderate Reynolds number range in co-operation with the wind tunnel from Laboratoire de M´ecanique de Feiret Lille for large Reynolds number range. Measurements are conducted with the help of state-of-the-art techniques such as Laser Doppler Anemometry, Particle Image Velocimetry and electronic pressure sensors.
Author: Ronald Lee Panton
Publisher: Computational Mechanics
Published: 1997
Total Pages: 448
ISBN-13:
DOWNLOAD EBOOKWhy is wall turbulence self-sustaining? In this book well-regarded researchers not only discuss what they know and believe, but also speculate on ideas that still require numerical or experimental testing and verification. An initial brief history of boundary layer structure research is followed by chapters on experimental information and specific topics within the subject. There are then sections on computational aspects.