Effects of Pressure Gradients on Turbulent Boundary Layer Flow Over a Flat Plate with Riblets PDF Download
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Author: Franklin Dement
Publisher:
ISBN: 9781423546672
Category :
Languages : en
Pages : 178
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Book Description
The Air Force Institute of Technology Boundary Layer Research Facility test section was modified to create controlled non-zero streamwise pressure gradients. The capability of the modified facility to reproduce theoretical laminar boundary layer velocity profiles and to create a self- preserving flow with an adverse streamwise pressure gradient was verified with three-dimensional laser Doppler anemometry. The effects of streamwise adverse and favorable pressure gradients on turbulent boundary layer flow characteristics (velocity profiles, turbulence and skin friction) and vortex formation over a flat plate with riblets at low speed (U = 5 mIs) were studied. Normal and spanwise velocity profiles for both pressure gradients showed the presence of paired counter-rotating vortices nested within the riblet valleys. These flow structures increased drag and significantly altered near-wall flow compared to a smooth plate turbulent boundary layer. The adverse pressure gradient tended to degrade these vortices as the flow progressed.
Author: Franklin Dement
Publisher:
ISBN: 9781423546672
Category :
Languages : en
Pages : 178
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Book Description
The Air Force Institute of Technology Boundary Layer Research Facility test section was modified to create controlled non-zero streamwise pressure gradients. The capability of the modified facility to reproduce theoretical laminar boundary layer velocity profiles and to create a self- preserving flow with an adverse streamwise pressure gradient was verified with three-dimensional laser Doppler anemometry. The effects of streamwise adverse and favorable pressure gradients on turbulent boundary layer flow characteristics (velocity profiles, turbulence and skin friction) and vortex formation over a flat plate with riblets at low speed (U = 5 mIs) were studied. Normal and spanwise velocity profiles for both pressure gradients showed the presence of paired counter-rotating vortices nested within the riblet valleys. These flow structures increased drag and significantly altered near-wall flow compared to a smooth plate turbulent boundary layer. The adverse pressure gradient tended to degrade these vortices as the flow progressed.
Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 568
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Book Description
Author: Mohamed Gad-el-Hak
Publisher: Springer Science & Business Media
ISBN: 3540696725
Category : Science
Languages : en
Pages : 533
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Book Description
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.
Author: K. Krishna Prasad
Publisher: Springer Science & Business Media
ISBN: 9401117012
Category : Technology & Engineering
Languages : en
Pages : 206
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Book Description
The thrust of modern research on turbulence in fluids is concerned with coherent structures and modelling. Riblets have been shown to reduce drag, and the papers presented in this volume tackle the main question of the mechanism responsible for this behaviour in turbulent flow. The contributions in this volume were presented at the Sixth Drag Reduction Meeting held at Eindhoven during November 1991. This volume will be a useful reference work for engineers, physicists and applied mathematicians interested in the topic of fluid turbulence.
Author: Ronald Lee Panton
Publisher: Computational Mechanics
ISBN:
Category : Science
Languages : en
Pages : 448
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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.
Author: Jean Piquet
Publisher: Springer Science & Business Media
ISBN: 3662035596
Category : Technology & Engineering
Languages : en
Pages : 767
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Book Description
obtained are still severely limited to low Reynolds numbers (about only one decade better than direct numerical simulations), and the interpretation of such calculations for complex, curved geometries is still unclear. It is evident that a lot of work (and a very significant increase in available computing power) is required before such methods can be adopted in daily's engineering practice. I hope to l"Cport on all these topics in a near future. The book is divided into six chapters, each· chapter in subchapters, sections and subsections. The first part is introduced by Chapter 1 which summarizes the equations of fluid mechanies, it is developed in C~apters 2 to 4 devoted to the construction of turbulence models. What has been called "engineering methods" is considered in Chapter 2 where the Reynolds averaged equations al"C established and the closure problem studied (§1-3). A first detailed study of homogeneous turbulent flows follows (§4). It includes a review of available experimental data and their modeling. The eddy viscosity concept is analyzed in §5 with the l"Csulting ~alar-transport equation models such as the famous K-e model. Reynolds stl"Css models (Chapter 4) require a preliminary consideration of two-point turbulence concepts which are developed in Chapter 3 devoted to homogeneous turbulence. We review the two-point moments of velocity fields and their spectral transforms (§ 1), their general dynamics (§2) with the particular case of homogeneous, isotropie turbulence (§3) whel"C the so-called Kolmogorov's assumptions are discussed at length.
Author: A.V. Boiko
Publisher: Springer Science & Business Media
ISBN: 3662047659
Category : Technology & Engineering
Languages : en
Pages : 273
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Book Description
The Origin of Species Charles Darwin The origin of turbulence in fluids is a long-standing problem and has been the focus of research for decades due to its great importance in a variety of engineering applications. Furthermore, the study of the origin of turbulence is part of the fundamental physical problem of turbulence description and the philosophical problem of determinism and chaos. At the end of the nineteenth century, Reynolds and Rayleigh conjectured that the reason of the transition of laminar flow to the 'sinuous' state is in stability which results in amplification of wavy disturbances and breakdown of the laminar regime. Heisenberg (1924) was the founder of linear hydrody namic stability theory. The first calculations of boundary layer stability were fulfilled in pioneer works of Tollmien (1929) and Schlichting (1932, 1933). Later Taylor (1936) hypothesized that the transition to turbulence is initi ated by free-stream oscillations inducing local separations near wall. Up to the 1940s, skepticism of the stability theory predominated, in particular due to the experimental results of Dryden (1934, 1936). Only the experiments of Schubauer and Skramstad (1948) revealed the determining role of insta bility waves in the transition. Now it is well established that the transition to turbulence in shear flows at small and moderate levels of environmental disturbances occurs through development of instability waves in the initial laminar flow. In Chapter 1 we start with the fundamentals of stability theory, employing results of the early studies and recent advances.
Author: E. L. Houghton
Publisher: Elsevier
ISBN: 0080493858
Category : Technology & Engineering
Languages : en
Pages : 605
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Book Description
Aerodynamics for Engineering Students, Fifth Edition, is the leading course text on aerodynamics. The book has been revised to include the latest developments in flow control and boundary layers, and their influence on modern wing design as well as introducing recent advances in the understanding of fundamental fluid dynamics. Computational methods have been expanded and updated to reflect the modern approaches to aerodynamic design and research in the aeronautical industry and elsewhere, and the structure of the text has been developed to reflect current course requirements. The book is designed to be accessible and practical. Theory is developed logically within each chapter with notation, symbols and units well defined throughout, and the text is fully illustrated with worked examples and exercises. The book recognizes the extensive use of computational techniques in contemporary aeronautical design. However, it can be used as a stand-alone text, reflecting the needs of many courses in the field for a thorough grounding in the underlying principles of the subject. The book is an ideal resource for undergraduate and postgraduate students in aeronautical engineering. The classic text, expanded and updated.Includes latest developments in flow control, boundary layers and fluid dynamics.Fully illustrated throughout with illustrations, worked examples and exercises.
Author: United States. National Advisory Committee for Aeronautics
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1200
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Book Description
Includes the Committee's Technical reports no. 1-1058, reprinted in v. 1-37.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 836
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Book Description
