Download or read book The Turbulence Structure of Equilibrium Boundary Layers written by Peter Bradshaw and published by . This book was released on 1966 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements in boundary layers are discussed together with existing data and some new measurements in boundary layers in zero pressure gradient. It is shown that the small-scale turbulence is nearly universal, and that the large-eddy motion is nearly the same. Comparisons with the free mixing layer suggest that the large eddies consist of mixing jets.
Download or read book The Structure of Equilibrium Turbulent Boundary Layers written by Sandy Fong and published by . This book was released on 1995 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulent Shear Flows 5 written by Franz Durst and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first four symposia in the series on turbulent shear flows have been held alternately in the United States and Europe with the first and third being held at universities in eastern and western States, respectively. Continuing this pattern, the Fifth Symposium on Turbulent Shear Flows was held at Cornell University, Ithaca, New York, in August 1985. The meeting brought together more than 250 participants from around the world to present the results of new research on turbulent shear flows. It also provided a forum for lively discussions on the implications (practical or academic) of some of the papers. Nearly 100 formal papers and about 20 shorter communications in open forums were presented. In all the areas covered, the meeting helped to underline the vitality of current research into turbulent shear flows whether in experimental, theoretical or numerical studies. The present volume contains 25 of the original symposium presentations. All have been further reviewed and edited and several have been considerably extended since their first presentation. The editors believe that the selection provides papers of archival value that, at the same time, give a representative statement of current research in the four areas covered by this book: - Homogeneous and Simple Flows - Free Flows - Wall Flows - Reacting Flows Each of these sections begins with an introductory article by a distinguished worker in the field.
Download or read book The Structure of Turbulent Shear Flow written by A. A. R. Townsend and published by Cambridge University Press. This book was released on 1976 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: Develops a physical theory from the mass of experimental results, with revisions to reflect advances of recent years.
Download or read book The Effect of Pressure Gradient on the Structure of an Equilibrium Turbulent Boundary Layer written by Ting-Kwo Lei and published by . This book was released on 1993 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurements and Modeling of the Mean and Turbulent Flow Structure in High Speed Rough Wall Non Equilibrium Boundary Layers written by and published by . This book was released on 2010 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: The response of a supersonic high Reynolds number turbulent boundary layer flow subjected to mechanical distortions was experimentally examined. Local disturbances were introduced via small-scale wall patterns, and global distortions were induced through streamline curvature driven pressure gradients. Local surface topologies included k-type diamond and d-type square elements; a smooth wall was examined for comparison purposes. Three global distortions were studied with each of the three surface topologies. Measurements included planar contours of the mean and fluctuating velocity pressure sensitive paint and schlieren photography. The velocity data were acquired with sufficient resolution to characterize the mean and turbulent flow structure and to examine interactions between the local surface roughness distortions and the imposed pressure gradients on the turbulence production. A strong response to both the local and global distortions was observed with the diamond elements, where the effect of the elements extended into the outer-regions of the boundary layer. It was shown that the primary cause for the observed response was the result of local shock and expansion waves modifying the turbulence structure and production. By contrast, the square elements showed a less pronounced response to local flow distortions as the waves were significantly weaker. However, the frictional losses were higher for the blunter square roughness elements. Detailed quantitative characterizations of the turbulence flow structure and the associated production mechanisms are described herein. These experiments demonstrate fundamental differences between supersonic and subsonic rough-wall flows, and the new understanding of the underlying mechanisms provides a scientific basis to systematically modify the mean and turbulence flow structure all the way across supersonic boundary layers.
Download or read book Analysis of Turbulent Flows with Computer Programs written by Tuncer Cebeci and published by Elsevier. This book was released on 2004 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modelling and Computation of Turbulent Flows has been written by one of the most prolific authors in the field of CFD. Professor of aerodynamics at SUPAERO and director of DMAE at ONERA, the author calls on both his academic and industrial experience when presenting this work. The field of CFD is strongly represented by the following corporate companies; Boeing; Airbus; Thales; United Technologies and General Electric, government bodies and academic institutions also have a strong interest in this exciting field. Each chapter has also been specifically constructed to constitute as an advanced textbook for PhD candidates working in the field of CFD, making this book essential reading for researchers, practitioners in industry and MSc and MEng students. * A broad overview of the development and application of Computational Fluid Dynamics (CFD), with real applications to industry * A Free CD-Rom which contains computer program's suitable for solving non-linear equations which arise in modeling turbulent flows * Professor Cebeci has published over 200 technical papers and 14 books, a world authority in the field of CFD
Download or read book Study of the Structure of Turbulence in Accelerating Transitional Boundary Layers written by Michael F. Blair and published by . This book was released on 1987 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: A combined experimental and analytical program has been conducted to examine transitional, accelerating boundary layer flows with high levels of freestream turbulence. An earlier program focused on measurement of transitional heat transfer distributions for four combinations of streamwise acceleration and freestream turbulence. The present program was designed to document the boundary layer turbulence structure and spectral distributions for the same four test conditions. The results from the present program have shown that transition in accelerating flows consists of an acceleration dominated stage of slowly developing intermittency followed by a second stage with the same general characteristics as zero-pressure-gradient transition. Conditionally sampled fluctuating velocity profile measurements indicated that the boundary layer turbulence was highly anisotropic in the early stages of transition. Conditionally sampled mean velocity measurements showed that within the intermittent turbulent patches the mean velocity profiles were very similar to those of an equilibrium turbulent boundary layer. Spectral distribution data indicated that preferred amplification of the most unstable (as predicted by linear stability theory) frequencies occurred upstream of the onset of transitional bursting. In addition to the experimental portion of this investigation, numerical experiments were undertaken to assess the ability of currently existing methods to predict heat transfer during transition in accelerating flows.
Download or read book A Study of Turbulent Boundary Layer Structure written by John Leask Lumley and published by . This book was released on 1986 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Favourable Pressure Gradient on Turbulence in Boundary Layers written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis explores the effects of favourable pressure gradient on the structure of turbulent boundary layers (TBL). In this context, the structure of three types of boundary layers namely a zero-pressure-gradient boundary layer, equilibrium boundary layers under favourable pressure gradient and relaminarising boundary layers is investigated mostly from the point of view of large-scale dynamics. This covers a whole range of flows on the so-called Reynolds number - pressure gradient diagram - from turbulent zero pressure gradient flows to relaminarising flows at relatively low Reynolds numbers. The study of turbulent and relaminarising boundary layers is carried out primarily using direct numerical analyses and some limited experiments in this thesis. The direct numerical simulations (DNS) of a zero-pressure-gradient turbulent boundary layer (ZPG TBL) is validated against the experimental and DNS data available in the literature. Furthermore, the important question of time-averaged signature of a large scale vortex structure and its relation with the two-point correlations in the context of ZPG TBL is addressed. In this context, a synthetic flow consisting of hairpin vortex structures is generated. The two-point correlations in the synthetic TBL and a real TBL are found to be qualitatively similar. This shows that the vortex structure leaves a time-averaged footprint in the form of correlations of velocity and vorticity. A study of two-point correlations in a real TBL shows that the structure angle deduced from two-point correlations varies with wall-normal location. The structure angle is small near the wall and increases away from the wall in agreement with the previous studies. The small angle close to the wall signifies the presence of streamwise structure. Away from the wall, this streamwise coherence is lost and the correlation contours become more isotropic. The presence of the wall and the mean shear affects smaller scales making them anisotropic close to th
Download or read book Analysis of Turbulent Boundary Layers written by Tuncer Cebeci and published by Elsevier. This book was released on 2012-12-02 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculating two-dimensional and axisymmetric laminar and turbulent boundary layers. This book will be useful to readers who have advanced knowledge in fluid mechanics, especially to engineers who study the important problems of design.
Download or read book An Investigation of the Structure of Equilibrium Turbulent Boundary Layers written by Lionel Fitzroy East and published by . This book was released on 1979 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Equilibrium turbulent boundary layers written by G. L. Mellor and published by . This book was released on 1963 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: A particular form for an effective or eddy viscosity is hypothesized and considered in conjunction with the boundary layer equations for cases where the pressure gradient parameter is held constant. Precise solutions are obtained for accelerating and decelerating flows in the range, beta infinity; the solutions span the complete boundary layer profile with the exception of the small viscous sublayer region. Comparison of the calculated velocity profiles with zero pressure gradient data and Clauser's and Stratford's decelerating flow data is excellent. For large values of beta the influence of the pressure gradient dominates the influence of the wall shear stress; defect profiles should then be presented in the form, U sub p, instead of U sub tau where U sub p is a pressure velocity and U sub tau is the conventional skin function velocity. (Author).
Download or read book The Effect of Transverse Curvature on the Fluctuating Wall Pressure and Structure of Boundary Layer Turbulence written by and published by . This book was released on 1993 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document consists of the text and viewgraphs of a paper presented at the ONR Workshop on Nonequilibrium Turbulence held at Arizona State University in Tempe, Arizona, from 10-1 2 March 1993. This workshop was the first step of an ONR Accelerated Research Initiative (ARI) to establish the state-of-the-art for theory, computation, and experimentation relevant to turbulence in a nonequilibrium state, or, more generally, to turbulence in complex flows. The overall goal of the initiative is to understand the behavior of turbulence in such complex conditions in order to advance our prediction and control capabilities. When a cylinder in axial flow is sufficiently long and thin, the growth of the boundary layer results in its thickness exceeding the radius of the cylinder such that the three-dimensional effects due to transverse curvature cannot be neglected. With this condition, the wall of the cylinder provides less constraint on the outer flow and motion of eddies than is experienced in an equilibrium flat plate boundary layer, introducing an avenue for enhanced inner-layer/outer-layer interaction and modified turbulence activity. In this paper, we present results of measurements of the fluctuating wall pressure and turbulent streamwise velocity in the turbulent boundary layer on a cylinder in axial flow to identify the coherent structures that contribute to the fluctuating pressure at the wall. Determining the influence of transverse curvature on the relationship between the wall pressure and velocity field allows examination of its effect on the structure of equilibrium boundary layer turbulence.
Download or read book Investigation of Turbulent Boundary Layers Subjected to Internally Or Externally Imposed Time Dependent Transverse Shear written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Both experimental and modeling efforts are aimed at understanding the non-equilibrium effects introduced by a 2-D turbulent boundary layer suddenly subjected to transverse wall shear. A new turbulence model has been developed which can be used to predict the Reynolds stress development in 3-D shear flows. This theta-l model allows for a misalignment to occur between the stress and strain as observed in 3-D turbulent boundary layers. The misalignment is determined by accounting for the flow history through solving a transport equation (first derived by Bradshaw, 1971) for theta. Excellent agreement is observed for both mean profiles and Reynolds stress when compared with the experiments of Driver and Johnston (1990). For the experiments, a 36' long 18" diameter cylinder surface is used. One section of the model is designed to rotate about its axis; thereby, introducing non-equilibrium effects into the developing 2-D boundary layer. Stereoscopic PIV is being used to acquire all three components of the velocity in both the x-y and x-z planes. Comparison of the detailed experimental results with subsequent modifications of the modeling should result in improved non-equilibrium turbulence prediction capabilities.
Download or read book Turbulent Boundary Layers in Strong Adverse Pressure Gradients written by W. H. Schofield and published by . This book was released on 1980 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new analysis of equilibrium boundary layers based on the Schoheld and Perry defect law for flow in moderate to strong adverse pressure gradient is presented. The conditions derived for self-preserving or precise equilibrium boundary layers differ from those given by previous analyses based on the usual velocity defect law. It is shown that nine observed boundary layers on smooth walls conform to these new conditions for equilibrium flow. As the analytical expression for the Schofield and Perry defect law does not vary with pressure gradient an explicit expression for the shear stress profile in any equilibrium layer can be derived. Predicted shear stress profiles show good agreement with experimental data. Limits for the flow parameters within which equilibrium boundary layers can exist are derived and it is shown that observed boundary layers fall within these limits. Results by previous workers are shown to be consistent with these limits.
Download or read book The Structure of Turbulent Boundary Layers and Shock Wave Boundary Layer Interactions written by and published by . This book was released on 1993 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report is the Final Technical Report for AFOSR Grant 89-0420, monitored by Dr James McMichael, for the period June 15, 1989 to October 14, 1992. Under this program, research was performed (1) to describe the structure of the large-scale motions in supersonic turbulent boundary layers, (2) to study the interaction of that turbulence with shock waves and strategies for controlling the interaction, (3) to differentiate between Mach and Reynolds number effects on turbulence structure in wall-bounded flows, and (4) to develop and implement new non-intrusive diagnostic techniques. The research is aimed at providing physical insight, and scaling information, for the development of turbulence models appropriate for supersonic shear layers. The primary experimental means used in these investigations were the Rayleigh scattering technique to study the instantaneous density field, the RELIEF line tagging method to study the instantaneous velocity field, and a dual hot-wire technique to obtain simultaneous velocity and density signals ... Boundary layers, Turbulence, Shock wave boundary layer interaction.
