Download or read book The Influence of Transverse curvature of the Velocity in Thick Axisymmetric Turbulent Boundary Layers written by Heinrich Eickoff and published by . This book was released on 1982 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Influence of Transverse Curvature on the Velocity Law in Thick Axisymmetric Turbulent Boundary Layers written by Heinrich Eickhoff and published by . This book was released on 1982 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Equations of a Thick Axisymmetric Turbulent Boundary Layer written by Virendrakumar Chaturbhai Patel and published by . This book was released on 1973 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: An examination of the Reynolds equations for axisymmetric turbulent flow where the thickness of the boundary layer is of the same order as the transverse radius of curvature of the surface shows that neither the boundary layer nor the potential flow outside it may be calculated independently of the other, owing to significant interactions between the two flow regimes. Following a discussion of various procedures for extending conventional thin boundary-layer calculation methods to treat thick axisymmetric turbulent boundary-layers, a method is proposed for the simultaneous solution of the boundary layer and the potential flow equations, allowing the two flow regimes to interact. (Author Modified Abstract).
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 Thick Axisymmetric Turbulent Boundary Layer and Near Wake of a Low drag Body of Revolution written by Virendrakumar Chaturbhai Patel and published by . This book was released on 1977 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: Detailed measurements of pressure distributions, mean velocity profiles and Reynolds stresses were made in the thick, axisymmetric boundary layer and the near wake of a low-drag body of revolution. The data are presented in graphical as well as tabular form for convenience in later analysis. These measurements shed some light on the joint influence of transverse and longitudinal surface curvatures and pressure gradients on the boundary-layer development and on the manner in which an axisymmetric boundary layer becomes a fully-developed wake. Apart from giving a complete set of data on such an important flow configuration, the measurements should provide a fairly rigorous test case for some of the recent turbulence closure models which claim a level of generality not achieved by the older phenomenological models. By inclusion of recently proposed modifications to account for the effects of the extra rates of strain on the turbulence length scale arising from longitudinal and transverse surface curvatures, it is shown that the boundary layer in the tail region of a body of revolution is dominated by the extra strain rates and that more research is needed to account for them properly even in the most recent calculation procedures.
Download or read book Thick Axisymmetric Turbulent Boundary Layer and Wake of a Low drag Body written by Yu-Tai Lee and published by . This book was released on 1978 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Detailed measurements of pressure distributions, mean velocity profiles and Reynolds stresses were made in the thick, axisymmetric boundary layer and the near wake of a low-drag body of revolution. These measurements shed some light on the joint influence of transverse and longitudinal surface curvatures and pressure gradients on the boundary-layer development and on the manner in which an axisymmetric boundary layer becomes a fully-developed wake. The present data have been used to provide an independent check on the accuracy of the simple integral method proposed by Patel, and its extension to the calculation of the near wake made by Nakayama, Patel and Landweber. Calculations have also been performed using the differential equations of the thick axisymmetric turbulent boundary layer and a rate equation for the Reynolds stress derived from the turbulent kinetic-energy equation along the lines suggested by Bradshaw and others. It is shown that the boundary layer in the tail region of a body of revolution is dominated by the extra strain rates arising from longitudinal and transverse surface curvatures. A new differential method is incorporated into the iterative procedure developed by Nakayama, Patel and Landweber for the solution of the interaction between the boundary layer, the wake and the external inviscid flow. The results of the iterative method have been compared with the experimental data obtained from the present low-drag body and those obtained earlier on a modified spheroid to demonstrate agreement. (Author).
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 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 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 Curvature effects of three dimensional thick stern boundary layers written by Yu-Tai Lee and published by . This book was released on 1985 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thick boundary-layer equations, including the variation of the metric coefficients with distance normal to the surface, are solved from the nose to the tail of an elongated three-dimensional body. Iteration between potential and boundary-layer flow solutions is adopted to obtain a converged solution in the stern region. The complete procedure makes use of Keller's box numerical scheme in a non-orthogonal curvilinear coordinate system and an isotropic eddy-viscosity model for the Reynolds stress tensor in both streamwise and crosswise directions. The numerical method allows the calculation of flows in which the crosswise component of velocity cntains regions of flow reversal across the boundary layer. The inviscid pressure is determined by using the Hess-Smith method. The program is validated for an axisymmetric body, and then the calculations are compared with measurements for two three-dimensional bodies having elliptical transverse sections. Keywords: Thick turbulent stern flows; Longitudinal and transverse curvature effects; Turbulence modeling; and Eddy viscosity.
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 A Unified View of the Law of the Wall Using Mixing length Theory written by Virandrakumar Chaturbhai Patel and published by . This book was released on 1972 with total page 70 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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1989 with total page 968 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 An Experimental Study of the Thick Turbulent Boundary Layer Near the Tail of a Body of Revolution written by V. C. Patel and published by . This book was released on 1973 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Detailed measurements of pressure distributions, mean velocity profiles and Reynolds stresses were made in the thick incompressible axisymmetric turbulent boundary layer near the tail of a body of revolution. The results indicate a number of important differences between the behavior of a thick and a thin boundary layer. Significant variations of static pressure and a low level of turbulence are noted. Thus in order to predict the behavior of the flow in the tail region of a body of revolution it does not appear possible to use conventional thin-boundary-layer calculation procedures. (Author Modified Abstract).
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:
