Download or read book On the Receptivity Problem for Goertler Vortices written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-10 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: The receptivity problem for Goertler vortices induced by wall roughness is investigated. The roughness is modelled by small amplitude perturbations to the curved wall over which the flow takes place. The amplitude of these perturbations is taken to be sufficiently small for the induced Goertler vortices to be described by linear theory. The roughness is assumed to vary in the spanwise direction on the boundary layer lengthscale, while in the flow direction the corresponding variation is on the lengthscale over which the wall curvature varies. In fact the latter condition can be relaxed to allow for a faster streamwise roughness variation so long as the variation does not become as fast as that in the spanwise direction. The function which describes the roughness is assumed to be such that its spanwise and streamwise dependences can be separated; this enables progress by taking Fourier or Laplace transforms where appropriate. The cases of isolated and distributed roughness elements are investigated and the coupling coefficient which relates the amplitude of the forcing and the induced vortex amplitude is found asymptotically in the small wavelength limit. It is shown that this coefficient is exponentially small in the latter limit so that it is unlikely that this mode can be stimulated directly by wall roughness. The situation at 0(1) wavelengths is quite different and this is investigated numerically for different forcing functions. It is found that an isolated roughness element induces a vortex field which grows within a wedge at a finite distance downstream of the element. However, immediately downstream of the obstacle the disturbed flow produced by the element decays in amplitude. The receptivity problem at larger Goertler numbers appropriate to relatively large wall curvature is discussed in detail. Denier, James P. and Hall, Philip and Seddougui, Sharon Unspecified Center...
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 On the Receptivity Problem for G rtler Vortices Vortex Motions Induced by Wall Roughness written by J. P. Denier and published by . This book was released on 1990 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Receptivity Problem for 0 1 Wavelength Goertler Vortices 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 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, we make an investigation of the receptivity of boundary layer flows to Gortler vortex modes. A study by Denier, Hall, and Seddougui (1991) of the generation of vortices by wall roughness elements concluded that such elements are extremely poor as mechanisms to stimulate short wavelength modes, but that analysis was in error. We re-examine this problem and demonstrate how the form of the wall roughness is crucial in determining the vortex stability characteristics downstream of the roughness. In particular, we investigate the cases of both isolated and distributed forcing functions and show that, in general, a distributed function is much more important in generating vortices than are either isolated roughness or freestream disturbances. Bassom, Andrew P. and Hall, Philip Unspecified Center NAS1-19480; RTOP 505-90-52-01...
Download or read book On the Receptivity Problem for 0 1 Wavelength G rtler Vortices written by Andrew P. Bassom and published by . This book was released on 1993 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper we make an investigation of the receptivity of boundary layer flows to Gortler vortex modes. A study by Denier, Hall, and Seddougui (1991) of the generation of vortices by wall roughness elements concluded that such elements are extremely poor as mechanisms to stimulate short wavelength modes. That work also examined the equivalent problem pertaining to O(1) wavelength modes but that analysis was in error. We re-examine this problem here and demonstrate how the form of the wall roughness is crucial in determining the vortex stability characteristics downstream of the roughness. In particular we investigate the cases of both isolated and distributed forcing functions and show that in general a distributed function is much more important in generating vortices than are either isolated roughness or free-stream disturbances. Receptivity, Vortex.
Download or read book On the Receptivity Problem for O 1 Wavelength Goertler Vortices written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1993 with total page 32 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 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Goertler Vortices in Growing Boundary Layers written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-08 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Goertler vortices are thought to be the cause of transition in many fluid flows of practical importance. A review of the different stages of vortex growth is given. In the linear regime, nonparallel effects completely govern this growth, and parallel flow theories do not capture the essential features of the development of the vortices. A detailed comparison between the parallel and nonparallel theories is given and it is shown that at small vortex wavelengths, the parallel flow theories have some validity; otherwise nonparallel effects are dominant. New results for the receptivity problem for Goertler vortices are given; in particular vortices induced by free stream perturbations impinging on the leading edge of the walls are considered. It is found that the most dangerous mode of this type can be isolated and it's neutral curve is determined. This curve agrees very closely with the available experimental data. A discussion of the different regimes of growth of nonlinear vortices is also given. Again it is shown that, unless the vortex wavelength is small, nonparallel effects are dominant. Some new results for nonlinear vortices of 0(1) wavelengths are given and compared to experimental observations. Hall, Philip Unspecified Center...
Download or read book Advances in Turbulence XI written by J. M. L. M. Palma and published by Springer Science & Business Media. This book was released on 2008-01-08 with total page 825 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume comprises the communications presented at the ETC 11, the EUROMECH European Turbulence conference held in 2007 in Porto. The scientific committee has chosen the contributions out of the following topics: Acoustics of turbulent flows; Atmospheric turbulence; Control of turbulent flows; Geophysical and astrophysical turbulence; Instability and transition; Intermittency and scaling; Large eddy simulation and related techniques; MHD turbulence; Reacting and compressible turbulence; Transport and mixing; Turbulence in multiphase and non-Newtonian flows; Vortex dynamics and structure formation; Wall bounded flows.
Download or read book Numerical Simulations Of Incompressible Flows written by Mohamed M Hafez and published by World Scientific. This book was released on 2003-01-23 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book consists of 37 articles dealing with simulation of incompressible flows and applications in many areas. It covers numerical methods and algorithm developments as well as applications in aeronautics and other areas. It represents the state of the art in the field.
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1991 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Nonlinear Development of the Most Unstable Goertler Vortex Mode written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1991 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flow Past Highly Compliant Boundaries and in Collapsible Tubes written by Peter W. Carpenter and published by Springer Science & Business Media. This book was released on 2003-03-31 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: The IUTAM Symposium on Flow in Collapsible Tubes and Past Other Highly Compliant Boundaries was held on 26-30 March, 2001, at the University of Warwick. As this was the first scientific meeting of its kind we considered it important to mark the occasion by producing a book. Accordingly, at the end of the Symposium the Scientific Committee met to discuss the most appropriate format for the book. We wished to avoid the format of the conventional conference book consisting of a large number of short articles of varying quality. It was agreed that instead we should produce a limited number of rigorously refereed and edited articles by selected participants who would aim to sum up the state of the art in their particular research area. The outcome is the present book. Peter W. Ca rpenter, Warwick Timothy J. Pedley, Cambridge May, 2002. VB SCIENTIFIC COMMITTEE Co-Chair: P.W. Carpenter, Engineering, Warwiek, UK Co-Chair: TJ. Pedley, DAMTP, Cambridge, UK V.V. Babenko, Hydromechanics, Kiev, Ukraine R. Bannasch, Bionik & Evolutionstechnik, TU Berlin, Germany C.D. Bertram, Biomedical Engineering, New South Wales, Australia M. Gad-el-Hak, Aerospace & Mechanical Engineering, Notre Dame, USA J.B. Grotberg, Biomedical Engineering, Michigan, USA. R.D. Kamm, Mechanical Engineering, MIT, USA Y. Matsuzaki, Aerospace Engineering, N agoya, Japan P.K. Sen, Applied Mechanics, IIT Delhi, India L. van Wijngaarden, Twente, Netherlands K-S. Yeo, Mechanical Engineering, NU Singapore.
Download or read book Fully Nonlinear Development of the Most Unstable Goertler Vortex in a Three Dimensional Boundary Layer written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1992 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fully Nonlinear Goertler Vortices in Constricted Channel Flows and Their Effect on the Onset of Separation written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1992 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Spatial Evolution of Long wavelength Goertler Vortices Governed by a Viscous inviscid Interaction written by and published by . This book was released on 1992 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Annual Index written by and published by . This book was released on 1991 with total page 1336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
