Download or read book Effects of Transverse Curvature on Low speed Turbulent Boundary layer Flow Along Circular Cylinders written by Clifford James Shirtliff and published by . This book was released on 1962 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Transverse Curvature Effects in Turbulent Boundary Layers written by P.M. Sforza and published by . This book was released on 1987 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effects of Streamwise Concave Curvature on Turbulent Boundary Layer Structure written by Albert H. Jeans and published by . This book was released on 1982 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concave curvature has a relatively large, unpredictable effect on turbulent boundary layers. Some, but not all previous studies suggest that a large-scale, stationary array of counter-rotating vortices exists within the turbulent boundary layer on a concave wall. The objective of the present study was to obtain a qualitative model of the flow field in order to increase our understanding of the underlying physics. A large free-surface water channel was constructed in order to perform a visual study of the flow. Streamwise components of mean velocity and turbulence intensity were measured using a hot film anemometer. The upstream boundary was spanwise uniform with a momentum thickness to radius of curvature of 0.05. Compared to flat wall flow, large-scale, randomly distributed sweeps and ejections were seen in the boundary layer on the concave wall. The sweeps appear to suppress the normal mechanism for turbulence production near the wall by inhibiting the bursting process. The ejections appear to enhance turbulence production in the outer layers as the low speed fluid convected from regions near the wall interacts with the higher speed fluid farther out. The large-scale structures did not occur at fixed spanwise locations, and could not be called roll cells or vortices. (Author).
Download or read book Some Characteristics of Turbulent Boundary Layers in Rapidly Accelerated Flows written by Paul F. Brinich and published by . This book was released on 1971 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analysis of time-mean-turbulent boundary layer velocity profiles measured in a rapidly accelerating flow suggests that the outer region of the velocity profiles consists of essentially inviscid, rotational flow. The extent of this inviscid outer region was observed in some cases to exceed 90 percent of what is ordinarily thought of as the turbulent boundary layer thickness. On the other hand, the inner frictional region of these velocity profiles appears to have turbulent characteristics similar to those of more conventional turbulent boundary layers. Hence, the outer edge boundary condition for this inner region is more properly the external rotational flow region than the free stream.
Download or read book Transverse Curvature Effects on Turbulent Boundary Layers written by M. C. Joseph and published by . This book was released on 1969 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transverse Curvature Effects on Turbulent Boundary Layers written by M. E. Joseph and published by . This book was released on 1969 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book WALL PRESSURE FLUCTUATIONS BENEATH AN AXIALLY SUMMERTRIC TURBULEN BOUNDARY LAYER ON A CYLINDER written by CHI-SHENG YANG, WILLIAM W. WILLMARTH and published by . This book was released on 1969 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Streamline Curvature on Turbulent Flow written by Peter Bradshaw and published by . This book was released on 1973 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Streamline curvature in the plane of the mean shear produces large changes in the turbulence structure of shear layers, usually an order of magnitude more important than normal pressure gradients and other terms in the mean-motion equations for curved flows. The effects on momentum and heat transfer in boundary layers are noticeable on typical wing sections and are very important on highly-cambered turbomachine blades: turbulence may be nearly eliminated on highly-convex surfaces, while on highly-concave surfaces momentum transfer by quasi-steady longitudinal vortices dominates the ordinary turbulence processes. The greatly enhanced mixing rates of swirling jets and the characteristic non-turbulent cores of trailing vortices are also consequences of the effects of streamline curvature on the turbulence structure. A progress report, comprises a review of current knowledge, a discussion of methods of predicting curvature effects, and a presentation of principles for the guidance of future workers.
Download or read book Advances in Turbulence 3 written by Arne V. Johansson and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 541 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book covers the following main topics: turbulence structure, transition, dynamical systems in relation to transition, turbulent combustion and mixing, turbulence affected by body forces, turbulence modeling, drag reduction, and novel experimental techniques.
Download or read book Experiments on Turbulent Bounday Layers Along a Circular Cylinder with and Without Separation written by Hans Fernholz and published by . This book was released on 1967 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Axisymmetric Turbulent Boundary Layer on an Extremely Long Cylinder written by Frank M. White and published by . This book was released on 1969 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analysis is presented which predicts the properties of an arbitrarily thick turbulent boundary layer in axial flow past a long cylinder. The study makes use of a modified form of the turbulent law-of-the-wall, which properly accounts for transverse curvature effects. Using this law, the theory which follows is then an exact solution to the axisymmetric equations of continuity and momentum in incompressible flow. Numerical results are given to show the effect of curvature on the various boundary layer characteristics. Skin friction and drag coefficients can be increased greatly with increasing curvature while boundary layer thickness is decreased. When defined in their axisymmetric form, the displacement and momentum thickness are both decreased by curvature. The velocity profile is flattened greatly and the shape factor approaches unity at large curvature. The failure of earlier power-law theories to make accurate predictions is shown to be due to their inadequate handling of the strong profile shape changes. (Author).
Download or read book Turbulent Boundary Layer on a Cylinder in Axial Flow written by and published by . This book was released on 1988 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report reviews research on the turbulent boundary layer that develops on a cylinder in axial flow. Experimental results indicate that the transverse curvature results in a higher coefficient of friction and a fuller velocity profile than for a planar boundary layer. However, appropriate scaling laws and nondimensional scaling parameters are still elusive. The few turbulence measurements such as Reynolds stress and intermittency that are available for a cylindrical boundary layer suggest that the distribution of turbulent quantities in the boundary layer is somewhat different from a planar boundary layer, particularly as the boundary layer becomes thick compared to the radius of the cylinder. This is most likely a result of the tendency for a cylindrical boundary layer to become wake-like as the cylinder becomes very small. Measurements of turbulence intensity and detection of turbulence-generating events in a cylindrical boundary layer suggest that the mechanism for the production of turbulence near the wall is similar to that for other wall-bounded flows. However, there is experimental evidence that the outer flow interacts with the near-wall flow to modify the generation of turbulence. Suggestions for further work include more comprehensive and sophisticated measurements of turbulent quantities in cylindrical boundary layers as well as computational modeling.
Download or read book The Transverse Curvature Effect in Compressible Axialy symmetric Laminar Boundary Layer Flow written by Ronald F. Probstein and published by . This book was released on 1954 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Analytical Solution of the Thick Axisymmetric Turbulent Boundary Layer on a Long Cylinder of Constant Radius written by Nuray Denli and published by . This book was released on 1978 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two similarity laws for a thick, axisymmetric, turbulent boundary layer on a long circular cylinder have been established. The validity of the assumption of constant-stress moment in the law-of-the-wall region is analyzed under the assumption of similarity. A new logarithmic mixing length, which takes into consideration the effect of transverse curvature on turbulence, is proposed for the law-of-the-wall region. With this logarithmic mixing-length models, the mean-flow momentum equation yields a law-of-the-wall relation in terms of the exponential integral in the logarithmic portion of the inner layer. Comparisons with available data and other proposed relations reveal that this logarithmic law gives a definite improvement. Also a mathematical explanation is given as to why the cylinder data do not deviate appreciably from the classical two-dimensional law-of-the-wall, even though it is observed that the turbulent characteristics, such as the size of large eddies and the turbulent intensities are much smaller than for a flat plate.
Download or read book The Transverse Curvature Effect in Compressible Axially symmetric Laminar Boundary Layer Flow Including the Effects of Pressure Gradient written by David Elliott and published by . This book was released on 1954 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:
