Download or read book Secondary Instabilities in Compressible Boundary Layers written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1990 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper examines secondary instabilities in compressible boundary layers at Mach numbers M at = 0, 0.8, 1.6, and 4.5. We find that there is a broad-dand of highly unstable 3-d secondary disturbances whose growth rates increase with increasing primary wave amplitude. At M
Download or read book Secondary Instability of Compressible Boundary Layer to Subharmonic Three dimensional Disturbances written by Nabil M. El-Hady and published by . This book was released on 1988 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spatial Three dimensional Secondary Instability of Compressible Boundary layer Flows written by Nabil M. El-Hady and published by . This book was released on 1989 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Secondary Instability of Compressible Boundary Layer to Subharmonic Three Dimensional Disturbances written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-11 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three-dimensional linear secondary instability theory is extended for compressible boundary layers on a flat plate in the presence of finite amplitude Tollmien-Schlichting (T-S) waves. The focus is on principal parametric resonance responsible for the strong growth of harmonics in a low disturbance environment. El-Hady, Nabil M. Unspecified Center NAG1-729; RTOP 505-60-21-01...
Download or read book Spatial Three Dimensional Secondary Instability Compressible Boundary Layer Flows written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-11 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three-dimensional linear secondary instability theory is extended for compressible and high Mach number boundary layer flows. The small but finite amplitude compressible Tollmien-Schlichting wave effect on the growth of 3-D perturbations is investigated. The focus is on principal parametric resonance responsible for the strong growth of subharmonic in low disturbance environment. The effect of increasing Mach number on the onset, growth, the shape of eigenfunctions of the subharmonic is assessed, and the resulting vortical structure is examined. El-Hady, Nabil M. Unspecified Center NAS1-18599; RTOP 505-60-21-06...
Download or read book Stability of Separating Subsonic Boundary Layers written by Jamal A. Masad and published by . This book was released on 1994 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Instability and Transition written by M.Y. Hussaini and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 509 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to predict and control viscous flow phenomena is becoming increasingly important in modern industrial application. The Instability and Transition Workshop at Langley was extremely important in help§ ing the scientists community to access the state of knowledge in the area of transition from laminar to turbulent flow, to identify promising future areas of research and to build future interactions between researchers worldwide working in the areas of theoretical, experimental and computational fluid and aero dynamics. The set of two volume contains panel discussions and research contribution with the following objectives: (1) expose the academic community to current technologically important issues of instability and transitions in shear flows over the entire speed range, (2) acquaint the academic community with the unique combination of theoretical, computational and experimental capabilities at LaRC and foster interaction with these facilities. (3) review current state-of-the-art and propose future directions for instability and transition research, (4) accelerate progress in elucidating basic understanding of transition phenomena and in transferring this knowledge into improved design methodologies through improved transition modeling, and (5) establish mechanism for continued interaction.
Download or read book Secondary Instability of High speed Flows and the Influence of Wall Cooling and Suction written by Nabil M. El-Hady and published by . This book was released on 1992 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Upper branch Stability of Compressible Boundary Layer Flows written by J. S. B. Gajjar and published by . This book was released on 1989 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Instability and Transition written by M.Y. Hussaini and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: These two volumes contain the proceedings of the workshop on the Institute for Computer Instability and Transition, sponsored by Applications in Science and Engineering (ICASE) and the Langley Research Center (LaRC), during May 15 to June 9, 1989. The work shop coincided with the initiation of a new, focused research pro gram on instability and transition at LaRC. The objectives of the workshop were to (i) expose the academic community to current technologically important issues of instability and transition in shear flows over the entire speed range, (ii) acquaint the academic com munity with the unique combination of theoretical, computational and experimental capabilities at LaRC and foster interaction with these facilities, (iii) review current state-of-the-art and propose fu ture directions for instability and transition research, (iv) accelerate progress in elucidating basic understanding of transition phenomena and in transferring this knowledge into improved design methodolo gies through improved transition modeling, and (v) establish mech anisms for continued interaction. The objectives (i) to (iii) were of course immediately met. It is still premature to assess whether ob jectives (iv) and (v) are achieved. The workshop program consisted of tutorials, research presenta tions, panel discussions, experimental and computational demonstra tions, and collaborative projects.
Download or read book Stability of Three dimensional Compressible Boundary Layers written by Eli Reshotko and published by . This book was released on 1962 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spatial Three dimensional Secondary Instability of Compressibility Boundary layer Flows written by Nabil M. El-Hady and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Linear and Nonlinear PSE for Compressible Boundary Layers written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1993 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Instability and Transition in Compressible Boundary Layers written by and published by . This book was released on 1991 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results are presented for (a) Real gas effects and Gortler vortices, (b) Nonparallel effects on Gortler vortex growth of Sutherland Law fluids, (c) Secondary instability analysis of finite amplitude Gortler vortices at hypersonic speeds, (d) Effects of crossflow velocities on Gortler vortices, (e) Mode interactions in compressible flows, (f) Receptivity theory for Gortler vortices.
Download or read book Instability Transition and Turbulence written by M.Y. Hussaini and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the proceedings of the Workshop on In stability, Transition and Turbulence, sponsored by the Institute for Computer Applications in Science and Engineering (ICASE) and the NASA Langley Research Center (LaRC), during July 8 to August 2, 1991. This is the second workshop in the series on the subject. The first was held in 1989, and its proceedings were published by Springer-Verlag under the title "Instability and Transition" edited by M. Y. Hussaini and R. G. Voigt. The objectives of these work shops are to i) expose the academic community to current technologically im portant issues of transition and turbulence in shear flows over the entire speed range, ii) acquaint the academic community with the unique combination of theoretical, computational and experimental capabilities at LaRC and foster interaction with these capabilities, and iii) accelerate progress in elucidating the fundamental phenomena of transition and turbulence, leading to improved transition and turbulence modeling in design methodologies. The research areas covered in these proceedings include receptiv ity and roughness, nonlinear theories of transition, numerical simu lation of spatially evolving flows, modelling of transitional and fully turbulent flows as well as some experiments on instability and tran sition. In addition a one-day mini-symposium was held to discuss 1 recent and planned experiments on turbulent flow over a backward facing step.
Download or read book On the Nonlinear Stability of a High speed Axisymmetric Boundary Layer written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1991 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: The stability of a high speed, axisymmetric boundary layer is investigated using secondary instability theory and direct numerical simulation. Parametric studies based on temporal secondary instability theory identify subharmonic secondary instability as a likely path to transition on a cylinder at Mach 4.5. The theoretical predictions are validated by direct numerical simulation of temporally-evolving primary and secondary disturbances in an axisymmetric boundary-layer flow. At small amplitudes of the secondary disturbance, predicted growth rates agree to several significant digits with values obtained from the spectrally-accurate solution of the compressible Navier Stokes equations. Qualitative agreement persists to large amplitudes of secondary disturbance. Moderate transverse curvature is shown to significantly affect the growth rate of axisymmetric second mode disturbances, the likely candidates of primary instability. The influence of curvature on secondary instability is largely indirect but most probably significant, through modulation of the primary disturbance amplitude. Subharmonic secondary instability is shown to be predominantly inviscid in nature, and to account for spikes in the Reynolds stress components at or near the critical layer.
Download or read book Secondary Instabilities of G rtler Vortices in High Speed Boundary Layers written by Jie Ren and published by Springer. This book was released on 2017-10-27 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis first reveals the mechanism of Görtler instabilities and then demonstrates how transitions at hypersonic flows can be effectively controlled (either promoted or suppressed) with Görtler or Klebanoff modes. It focuses on understanding and controlling flow transitions from mild laminar to fully turbulent flows at high speeds—aspects that have become crucial at the dawn of an incredible era, in which hypersonic vehicles are becoming available. Once this occurs, it will be possible to travel from Beijing to Los Angeles within just 2 hours, and we will all live in a genuinely global village—and not just virtually, but physically. Görtler instabilities have often been used to promote flow transition in hypersonic vehicles. However, how Görtler instabilities are excited and how they evolve in hypersonic flows are questions that have yet to be answered.
