Download or read book Growth and Development of Roughness induced Stationary Crossflow Vortices written by Ronald Henry Radeztsky and published by . This book was released on 1994 with total page 878 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Roughness induced Generation of Crossflow Vortices in Three dimensional Boundary Layers written by Meelan Choudhari and published by . This book was released on 1993 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Stationary Crossflow Vortices on a Swept Wing written by R. H. Radeztsky and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Interaction of Stationary Crossflow Vortices and Tollmien Schlichting Waves in the Boundary Layer on a Rotating Disc written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-10-29 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are many fluid flows where the onset of transition can be caused by different instability mechanisms which compete among themselves. The interaction is considered of two types of instability mode (at an asymptotically large Reynolds number) which can occur in the flow above a rotating disc. In particular, the interaction is examined between lower branch Tollmien-Schlichting (TS) waves and the upper branch, stationary, inviscid crossflow vortex whose asymptotic structure has been described by Hall (1986). This problem is studied in the context of investigating the effect of the vortex on the stability characteristics of a small TS wave. Essentially, it is found that the primary effect is felt through the modification to the mean flow induced by the presence of the vortex. Initially, the TS wave is taken to be linear in character and it is shown (for the cases of both a linear and a nonlinear stationary vortex) that the vortex can exhibit both stabilizing and destabilizing effects on the TS wave and the nature of this influence is wholly dependent upon the orientation of this latter instability. Further, the problem is examined with a larger TS wave, whose size is chosen so as to ensure that this mode is nonlinear in its own right. An amplitude equation for the evolution of the TS wave is derived which admits solutions corresponding to finite amplitude, stable, traveling waves. Bassom, Andrew P. and Hall, Philip Unspecified Center...

Download or read book On the Interaction of Stationary Crossflow Vortices and Tollmien Schlichting Waves in the Boundary Layer on a Rotating Disc written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1989 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Speed Boundary Layer Transition written by Patrick Joseph McGuire and published by . This book was released on 2014 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Crossflow instability is primary cause of boundary-layer transition on swept wings used in high-speed applications. Delaying the downstream location of transition would drastically reduce the viscous drag over the wing surface, and subsequently improves the overall aircraft efficiency. By studying the development of instability growth rates and how they interact with the surroundings, researchers can control the crossflow transition location. Experiments on the 35° swept-wing model were performed in the NASA Langley 20-Inch Supersonic Wind Tunnel with Mach 2.0 flow conditions and 20 [mu]m tall discrete roughness elements (DRE) with varying spacing placed along the leading edge. Fluorene was used as the sublimating chemical in the surface flow visualization technique to observe the transition front and stationary crossflow vortex patterns in the laminar flow region. Spatial spectral decomposition was completed on high-resolution images of sublimating chemical runs using a newly developed image processing technique. Streamwise evolution of the vortex track wavelengths within the laminar boundary-layer region was observed. The spectral information was averaged to produce dominant modes present throughout the laminar region.

Download or read book Weakly Nonparallel and Curvature Effects on Stationary Crossflow Instability Comparison of Results from Multiple scales Analysis and Parabolized Stability Equations written by and published by . This book was released on 1995 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Concerning the Interaction of Non stationary Cross flow Vortices in a Three dimensional Boundary Layer written by Andrew P. Bassom and published by . This book was released on 1990 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Stability Characteristics of Stationary Crossflow Vortices in Three dimensional Boundary Layer written by Mitsuyoshi Kawakami and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nonlinear Stability of Non Stationary Cross Flow Vortices in Compressible Boundary Layers written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-09 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nonlinear evolution of long wavelength non-stationary cross-flow vortices in a compressible boundary layer is investigated and the work extends that of Gajjar (1994) to flows involving multiple critical layers. The basic flow profile considered in this paper is that appropriate for a fully three-dimensional boundary layer with O(1) Mach number and with wall heating or cooling. The governing equations for the evolution of the cross-flow vortex are obtained and some special cases are discussed. One special case includes linear theory where exact analytic expressions for the growth rate of the vortices are obtained. Another special case is a generalization of the Bassom & Gajjar (1988) results for neutral waves to compressible flows. The viscous correction to the growth rate is derived and it is shown how the unsteady nonlinear critical layer structure merges with that for a Haberman type of viscous critical layer. Gajjar, J. S. B. Unspecified Center NCC3-370; RTOP 505-90-5K...

Download or read book The Origin of Turbulence in Near Wall Flows written by A.V. Boiko and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Nonlinear Stability of Non stationary Cross flow Vortices in Compressible Boundary Layers written by and published by . This book was released on 1995 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experiments in Non linear Saturation of Stationary Crossflow Vortices in a Swept wing Boundary Layer written by Mark S. Reibert and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computations in Nonlinear Saturation of Stationary Crossflow Vortices in a Swept wing Boundary Layer written by Tim S. Haynes and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nonlinear Development of Gortler and Crossflow Vortices and Gortler Tollmien Schlichting Wave Interaction written by M. R. Malik and published by . This book was released on 1990 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: The problem of nonlinear development of Goertler vortices on a curved wall is studied within the framework of incompressible Navier-Stokes equations which are solved by a Fourier-Chebyshev spectral method. The results show that higher harmonics grow due to nonlinear effects; however, most of the energy remains in the fundamental mode. The computed flow field in the presence of a Goertler vortex is in qualitative agreement with the experimental data. The interaction of the Goertler vortex with a two-dimensional Tollmien-Schlichting wave is also studied and it is shown that the Tollmien-Schlichting wave grows faster than its linear theory growth rate when the amplitude of the Goertler vortex is sufficiently large. Due to nonlinear effects this interaction further leads to the development of oblique waves with spanwise wavelength equal to the Goertler vortex wavelength. The numerical method is also applied to study the nonlinear development of a stationary crossflow vortex in a Falkner-Skan-Cooke boundary layer. The crossflow vortex develops in a manner similar to that found earlier for rotating disk flow. The fundamental and the higher harmonics all tend to saturate when the integration is carried to large amplitudes. The computed velocity distribution clearly shows the emergence of the superharmonic which, however, does not dominate the fundamental mode. The Falkner-Skan-Cooke flow, modulated by the presence of the crossflow vortex, is found to be subject to a new secondary instability with large growth rates. (JHD).

Download or read book On the Receptivity Problem for Goertler Vortices Vortex Motions Induced by Wall Roughness written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1990 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Simulation and Control of Stationary Crossflow Vortices written by Vinan I. Mistry and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: