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Some Effects Of Sparsely Distributed Three Dimensional Roughness Elements On Two Dimensional Turbulent Boundary Layers
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Book Synopsis Some Effects of Sparsely Distributed Three-dimensional Roughness Elements on Two-dimensional Turbulent Boundary Layers by : Jacob George
Download or read book Some Effects of Sparsely Distributed Three-dimensional Roughness Elements on Two-dimensional Turbulent Boundary Layers written by Jacob George and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Structure of 2-D and 3-D Turbulent Boundary Layers with Sparsely Distributed Roughness Elements by :
Download or read book Structure of 2-D and 3-D Turbulent Boundary Layers with Sparsely Distributed Roughness Elements written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The present study deals with the effects of sparsely distributed three-dimensional elements on two-dimensional (2-D) and three-dimensional (3-D) turbulent boundary layers (TBL) such as those that occur on submarines, ship hulls, etc. This study was achieved in three parts: Part 1 dealt with the cylinders when placed individually in the turbulent boundary layers, thereby considering the effect of a single perturbation on the TBL; Part 2 considered the effects when the same individual elements were placed in a sparse and regular distribution, thus studying the response of the flow to a sequence of perturbations; and in Part 3, the distributions were subjected to 3-D turbulent boundary layers, thus examining the effects of streamwise and spanwise pressure gradients on the same perturbed flows as considered in Part 2. The 3-D turbulent boundary layers were generated by an idealized wing-body junction flow. Detailed 3-velocity-component Laser-Doppler Velocimetry (LDV) and other measurements were carried out to understand and describe the rough-wall flow structure. The measurements include mean velocities, turbulence quantities (Reynolds stresses and triple products), skin friction, surface pressure and oil flow visualizations in 2-D and 3-D rough-wall flows for Reynolds numbers, based on momentum thickness, greater than 7000. Very uniform circular cylindrical roughness elements of 0.38mm, 0.76mm and 1.52mm height (k) were used in square and diagonal patterns, yielding six different roughness geometries of rough-wall surface. For the 2-D rough-wall flows, the roughness Reynolds numbers, based on the element height (k) and the friction velocity, range from 26 to 131. Results for the 2-D rough-wall flows reveal that the velocity-defect law is similar for both smooth and rough surfaces, and the semi-logarithmic velocity-distribution curve is shifted by an amount depending on the height of the roughness element, showing that this amount is a function of roughness Reynolds number and the wall geometry.
Book Synopsis Effect of Distributed Three-dimensional Roughness and Surface Cooling on Boundary-layer Transition and Lateral Spread of Turbulence at Supersonic Speeds by : Albert L. Braslow
Download or read book Effect of Distributed Three-dimensional Roughness and Surface Cooling on Boundary-layer Transition and Lateral Spread of Turbulence at Supersonic Speeds written by Albert L. Braslow and published by . This book was released on 1959 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effects of Spacing and Geometry of Distributed Roughness Elements on a Two-Dimensional Turbulent Boundary Layer by :
Download or read book Effects of Spacing and Geometry of Distributed Roughness Elements on a Two-Dimensional Turbulent Boundary Layer written by and published by . This book was released on 2005 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is a study of the effects of distributed roughness elements on a two-dimensional turbulent boundary layer. Measurements were taken on a total of ten rough wall configurations: four involving Gaussian spikes, and six with circular cylindrical posts. Rough wall flows are particularly suited to study with Laser Doppler Velocimetry (LDV) due to the fact that measurements are required near a solid surface, as well has in highly turbulent fluid. The LDV system used in this study is a fine resolution (50pm), three-component, fiber-optic system. All mean velocities, Reynolds stresses, and triple products are measured. This study is unique in the range and variety of roughness cases for which data was taken. The data show that flow over a rough wall is characterized by high levels of turbulence near the roughness element peaks at the interface between low-speed, near-wall fluid and the higher speed fluid above. Behind an element, high-momentum fluid sweeps toward the wall, and there is a small region of ejection of low-momentum fluid. Cylindrical elements typically have larger magnitudes of turbulent stresses at their peaks compared to Gaussian elements. Trends in mean velocity profile parameters such as displacement height, roughness effect, and wake parameter are examined with respect to roughness element geometry and spacing.
Book Synopsis Effects of Various Shaped Roughness Elements in Two-dimensional High Reynolds Number Turbulent Boundary Layers by :
Download or read book Effects of Various Shaped Roughness Elements in Two-dimensional High Reynolds Number Turbulent Boundary Layers written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Modeling the effects of surface roughness is an area of concern in many practical engineering applications. Many current roughness models to this point have involved the use of empirical 'constants' and equivalent sand grain roughness. These underdeveloped concepts have little direct relationship to realistic roughness and cannot predict accurately and consistently the flow characteristics for different roughness shapes. In order to aid in the development of turbulence models, the present research is centered around the experimental investigation of seven various shaped single roughness elements and their effects on turbulence quantities in a two-dimensional turbulent boundary layer. The elements under scrutiny are as follows: cone, cone with spatial variations equal to the smallest sublayer structure length scale, cone with spatial variations equal to 2.5 times the smallest sublayer structure length scale, Gaussian-shaped element, hemisphere, cube aligned perpendicular to the flow (cube at 90)̊, and a cube rotated 45 ̊relative to the flow. The roughness element heights, k+, non-dimensionalized by the friction velocity (Utau) of the approaching turbulent boundary layer, are 145, 145, 145, 145, 80, 98, and 98 respectively. Analysis of a three-dimensional fetch of the same Gaussian-shaped elements described previously was also undertaken. In order to analyze the complex flow fields, detailed measurements were obtained using a fine-measurement-volume (50 micron diameter) three-velocity component laser-Doppler velocimetry (LDV) system.
Book Synopsis Three-dimensional Turbulent Boundary-layer Flow on Roughness Strip of Finite Width by : Walter H. Edling
Download or read book Three-dimensional Turbulent Boundary-layer Flow on Roughness Strip of Finite Width written by Walter H. Edling and published by . This book was released on 1976 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis 41st AIAA Aerospace Sciences Meeting & Exhibit by :
Download or read book 41st AIAA Aerospace Sciences Meeting & Exhibit written by and published by . This book was released on 2003 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effect of Roughness on Three-Dimensional Turbulent Boundary Layer by : P. A. Krogstad
Download or read book Effect of Roughness on Three-Dimensional Turbulent Boundary Layer written by P. A. Krogstad and published by . This book was released on 1982 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The paper describes a three-dimensional boundary-layer experiment on a rough surface. The data obtained are compared to a reference experiment having the same geometry and flow conditions but with a smooth surface. The boundary layer date are compared using scaling criteria developed from two-dimensional flows. It is found that the results, in terms of scaled variables, agree well in regions where pressure gradients are the dominant cause of three-dimensionality. In regions where shear stresses are more important, significant deviations in profile characteristics appear. A possible interpretation is that the degree of anisotropy is greater in three-dimensional rough boundary-layer flows than in the corresponding smooth-wall case. (Author).
Book Synopsis The Effects of Steady, Three-dimensional Perturbations in Boundary Layers by : Raymond Sedney
Download or read book The Effects of Steady, Three-dimensional Perturbations in Boundary Layers written by Raymond Sedney and published by . This book was released on 1974 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary purpose of this report is to survey the available information mainly experimental, on the subject. Most attention is given to the complex flow field resulting when a 3-D protuberance is introduced into a laminar boundary layer; less can be said about the turbulent case or 2-D protuberances because enough detailed, careful experiments have not been made. There are some features of the induced flow fields common to all speed ranges; applications range from flow in the atmospheric boundary layer to hypersonic vehicle problems. Some attempts to analyze the downstream flow are also summarized.
Book Synopsis AIAA Aerospace Sciences Meeting and Exhibit, 42nd by :
Download or read book AIAA Aerospace Sciences Meeting and Exhibit, 42nd written by and published by . This book was released on 2004 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis 40th AIAA Aerospace Sciences Meeting & Exhibit by :
Download or read book 40th AIAA Aerospace Sciences Meeting & Exhibit written by and published by . This book was released on 2002 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Three-dimensional Turbulent Boundary Layers by : O. Sendstad
Download or read book Three-dimensional Turbulent Boundary Layers written by O. Sendstad and published by . This book was released on 1992 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental Studies in Three-dimensional Turbulent Boundary Layers by : J. P. Johnston
Download or read book Experimental Studies in Three-dimensional Turbulent Boundary Layers written by J. P. Johnston and published by . This book was released on 1976 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: The various methods for measurement of the six components of the turbulence stress tensor are reviewed, and some of the data on the turbulent shear stress vector are presented to demonstrate the validity of current ideas for.
Book Synopsis Some Reynolds Number Effects on a Three-dimensional Turbulent Boundary Layer by : M. Semih-Olcmen
Download or read book Some Reynolds Number Effects on a Three-dimensional Turbulent Boundary Layer written by M. Semih-Olcmen and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis 21st AIAA Advanced Measurement and Ground Testing Technology Conference: 00-2375 - 002527 by :
Download or read book 21st AIAA Advanced Measurement and Ground Testing Technology Conference: 00-2375 - 002527 written by and published by . This book was released on 2000 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Interaction of a Three-Dimensional Roughness Element with a Laminar Boundary Layer by : P. S. Klebanoff
Download or read book Interaction of a Three-Dimensional Roughness Element with a Laminar Boundary Layer written by P. S. Klebanoff and published by . This book was released on 1987 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation is described that is directed toward extending the technical database and furthering our understanding of boundary layer transition induced by three-dimensional roughness elements. The investigation was carried out in an unsteady wind tunnel, principally with hemispherical roughness elements, in a well characterized zero-pressure gradient laminar boundary layer on a flat plate. Attention was directed toward the following aspects of the behavior of a three dimensional roughness element: (1) the critical Reynolds number of transition and the effect of aspect ratio thereon, (2) eddy generation is steady and unsteady flows, (3) is the fundamental process stability governed, and (4) the evolutionary change in mean velocity and intensity of the velocity fluctuation associated with the transition to fully developed turbulent flow.
Book Synopsis Roughness Effects on Boundary-layer Transition for Blunt-leading-edge Plates at Mach 6 by : Paul F. Holloway
Download or read book Roughness Effects on Boundary-layer Transition for Blunt-leading-edge Plates at Mach 6 written by Paul F. Holloway and published by . This book was released on 1966 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
