On the Lagrangian Description of Unsteady Boundary Layer Separation. Part 2


Book Description

A theory to explain the initial stages of unsteady separation was proposed by Van Dommelen and Cowley (1989). This theory is verified for the separation process that occurs at the equatorial plane of a sphere or a spheroid which is impulsively spun around an axis of symmetry. A Lagrangian numerical scheme is developed which gives results in good agreement with Eulerian computations, but which is significantly more accurate. This increased accuracy, and a simpler structure to the solution, also allows verification of the Eulerian structure, including the presence of logarithmic terms. Further, while the Eulerian computations broke down at the first occurrence of separation, it is found that the Lagrangian computation can be continued. It is argued that this separated solution does provide useful insight into the further evolution of the separated flow. A remarkable conclusion is that an unseparated vorticity layer at the wall, a familiar feature in unsteady separation processes, disappears in finite time. Vandommelen, Leon L. Glenn Research Center ...




Boundary-Layer Separation


Book Description

The IUTAM Symposium on Boundary-Layer Separation, suggested by the UK National Committee of Theoretical and Applied Mechanics and supported by the International Union of Theoretical and Applied Mechanics, was held at University College London on August 26-28, 1986. The proposed theme and scope of the Symposium were designed to help to bring about the necessary interaction between experimentalists, computationalists and theoreticians for the furthering of understanding in this challenging subject. The talks and discussions were aimed at representing the very wide range and application of separating-flow phenomena, which often substantially affect the whole of fluid dynamics at medium to large Reynolds numbers, covering in particular both laminar and turbulent flow, steady or unsteady, two- or three-dimensional, small or large-scale, incompressible or compressible, external or internal, from the experimental, computational and theoretical standpoints. It was intended that about 80 scientists would participate in the Symposium, with about 25 talks being delivered, to which poster sessions with 8 contributions were added subsequently. All the speakers and poster presenters were selected by the scientific committee, although two late replacements of speakers were required. Fruitful discussions, well led by the session chairmen, took place formally after each talk and after the poster sessions and informally on other occasions including the social events. The present proceedings of the Symposium appear to reflect much of the current state of experimental, computational and theoretical work and progress in boundary-layer separation. We hope that they provide also ideas, questions and stimulation, in addition to major recent developments.




Aerodynamics And Aeroacoustics - Proceedings Of The Symposium


Book Description

The aim of the symposium was to gather fellow researchers, colleagues and friends of Professor William R Sears, a member of the National Academy of Science and the Academy of Engineering, on the occasion of his 80th birthday. Professor Sears is a leader in Aerospace Science and Aerodynamics research and the symposium was held in honour of his work in these areas.The symposium focussed on four areas in aeronautical science in which Professor Sears has made major contributions. These are wing design, unsteady aerodynamics and separation, aeroacoustics and self-correcting wind tunnels.




Scientific and Technical Aerospace Reports


Book Description

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.




New Perspectives in Turbulence


Book Description

This collection of articles has its origin in a meeting which took place June 12-15, 1989, on the grounds of Salve Regina College in Newport, Rhode Island. The meeting was blessed by beautiful, balmy weather and an idyllic setting. The sessions themselves took place in Ochre Court, one of the elegant and stately old summer cottages for which Newport is acclaimed. Lectures were presented in the grand ballroom overlooking the famous Cliff Walk and Block Island Sound. Counter to general belief, the pleasant surroundings did not appear to encourage truancy or in any other way diminish the quality of the meeting. On the contrary, for the four days of the meeting there was a high level of excitement and optimism about the new perspectives in turbulence, a tone that carried over to lively dinner and evening discussions. The participants represented a broad range of backgrounds, extending from pure mathemat ics to experimental engineering. A dialogue began with the first speakers which cut across the boundaries and gave to the meeting a mood of unity which persisted.




Mechanics for a New Millennium


Book Description

This volume contains the proceedings of the 2000 International Congress of Theoretical and Applied Mechanics. The book captures a snapshot view of the state of the art in the field of mechanics and will be invaluable to engineers and scientists from a variety of disciplines.




Vorticity and Vortex Dynamics


Book Description

This book is a comprehensive and intensive monograph for scientists, engineers and applied mathematicians, as well as graduate students in fluid dynamics. It starts with a brief review of fundamentals of fluid dynamics, with an innovative emphasis on the intrinsic orthogonal decomposition of fluid dynamic process, by which one naturally identifies the content and scope of vorticity and vortex dynamics. This is followed by a detailed presentation of vorticity dynamics as the basis of later development. In vortex dynamics part the book deals with the formation, motion, interaction, stability, and breakdown of various vortices. Typical vortex structures are analyzed in laminar, transitional, and turbulent flows, including stratified and rotational fluids. Physical understanding of vertical flow phenomena and mechanisms is the first priority throughout the book. To make the book self-contained, some mathematical background is briefly presented in the main text, but major prerequisites are systematically given in appendices. Material usually not seen in books on vortex dynamics is included, such as geophysical vortex dynamics, aerodynamic vortical flow diagnostics and management.




Self-sustaining Mechanisms of Wall Turbulence


Book Description

Why 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.




Vortex Dynamics and Vortex Methods


Book Description

Understanding vortex dynamics is the key to understanding much of fluid dynamics. For this reason, many researchers, using a great variety of different approaches--analytical, computational, and experimental--have studied the dynamics of vorticity. The AMS-SIAM Summer Seminar on Vortex Dynamics and Vortex Methods, held in June 1990 at the University of Washington in Seattle, brought together experts with a broad range of viewpoints and areas of specialization. This volume contains the proceedings from that seminar. The focus here is on the numerical computation of high Reynolds number incompressible flows. Also included is a smaller selection of important experimental results and analytic treatments. Many of the articles contain valuable introductory and survey material as well as open problems. Readers will appreciate this volume for its coverage of a wide variety of numerical, analytical, and experimental tools and for its treatment of interesting important discoveries made with these tools.