Download or read book Experimental Investigation of a Spanwise Forced Mixing Layer written by A. Glezer and published by . This book was released on 1987 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: The occurrence of three-dimensional motion within a plane mixing layer results in a significant increase of the internal mixedness (mixing transition). The three-dimensional motion necessary for mixing is induced by streamwise, counter-rotating vortex pairs superimposed on the primary spanwise vortices. While their appearance in the plane mixing layer has been established, their origin and their evolution with increasing streamwise distance remains and enigma. Stability considerations indicate that an instability in the spanwise direction may lead to the generation of streamwise vorticity. This suggests that the flow may be susceptible to low level spanwise periodic forcing. Previous experiments have demonstrated that forcing allows the enhancement of individual instability modes and is an essential step towards understanding the evolution of the natural flow. Furthermore, application of forcing to the flow provides a powerful tool of considerable practical significance for the control of the downstream evolution. We have begun an experimental investigation of a plane mixing layer which is forced independently in the spanwise and streamwise directions. Our objective is to study the evolution of spanwise instability. Its role in the development of the plane mixing layer and possible interaction between the streamwise and spanwise instabilities. Forcing is applied by a spanwise line of discrete surface film heaters flush mounted on the flow partition. This technique enables us to study nonlinear interactions between various modes of spanwise and streamwise instabilities. Keywords: Mixing layer, Spanwise forcing, Coherent structures, Hotwires, Schilieren.
Download or read book An Experimental Investigation of the Formation of Secondary Vortices and the Generation of Small Scale Motion in a Spanwise Forced Plane Mixing Layer written by and published by . This book was released on 1992 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: The evolution of spanwise instability modes and 3-D pulsed disturbances leading to the formation of streamwise vortices in a plane mixing layer and subsequently to the onset of small-scale 3-D motion were studied in a closed-return water facility. Streamwise vortices may result from a spanwise core instability of the primary vortices, or a spanwise instability of the nominally 2-D strain field between them. These two instability modes were excited by time-harmonic wavetrains with spanwise phase or amplitude variations, respectively, synthesized by a mosaic of surface film heaters flush-mounted on the flow partition. The appearance of the streamwise vortices is accompanied by significant distortion in the transverse distribution of the streamwise velocity component. Inflection points, which are not present in corresponding velocity distributions of the unforced flow, indicate the formation of locally unstable regions of large shear in which broadband perturbations already present in the base flow undergo rapid amplification which is followed by breakdown to turbulence and mixing transition. The core instability of the primary vortices suggests itself as viable mechanism for the continuation of the mixing process far downstream of mixing transition. Pulsed excitation was produced by pulsed spanwise amplitude modulation of a spanwise-uniform time-harmonic carrier wave train synthesized by the surface film heaters. Schlieren visualization showed that the disturbance spreads rapidly in the streamwise and lateral directions as it is advected downstream, and causes a substantial distortion of the adjacent spanwise vortices.
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 Technical Reports Awareness Circular TRAC written by and published by . This book was released on 1988-05 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Recent Awards in Engineering written by and published by . This book was released on 1983 with total page 986 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA SP written by and published by . This book was released on 1993 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1988 with total page 1132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1989 with total page 898 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Turbulence 2 written by Hans-Hermann Fernholz and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Second European Turbulence Conference was held at the Technische Univer sitat Berlin, Federal Republic of Germany, from August 30th to September 2nd 1988 under the auspices of the European Mechanics Committee. It was primar ily devoted to fundamental aspects of turbulence, and aimed at bringing together engineers, physicists, and mathematicians. The scientific committee - serving also as Sub-committee of the European Turbulence Conference - consisted of the following members: G. Comte-Bellot (Lyon), H.-H. Fernholz and H.E. Fiedler (both from Berlin) as co-chairmen of the conference, U. Frisch (Nice), J.C.R. Hunt (Cambridge), E. Krause (Aachen), M. Landahl (Stockholm), A.M. Obukhov (Moscow), and G. Ooms (Amsterdam). The conference programme comprised 6 invited lectures and 94 contributions, presented either orally or at poster sessions. There were 165 participants from 18 countries. All papers published in these conference proceedings were, with the exception of the invited ones, again refereed by the members of the scientific committee. The main research topics discussed at this meeting were stability and gener ation of turbulence, effects of rotation, stratification and buoyancy forces, novel instrumentation, manipulation and control, boundary layers with separation and reattachment, computer simulation, turbulent diffusion, image analysis and flow visualization, vorticity dynamics and turbulence, and large-scale structures. We have taken the liberty of regrouping some papers following the submitted final versions for this volume. Authors may therefore find their paper under a different heading from that in the conference programme.
Download or read book Mechanical Engineering News written by and published by . This book was released on 1986 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Parallel Computational Fluid Dynamics written by Kenli Li and published by Springer. This book was released on 2014-03-08 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the 25th International Conference on Parallel Computational Fluid Dynamics, ParCFD 2013, held in Changsha, China, in May 2013. The 35 revised full papers presented were carefully reviewed and selected from more than 240 submissions. The papers address issues such as parallel algorithms, developments in software tools and environments, unstructured adaptive mesh applications, industrial applications, atmospheric and oceanic global simulation, interdisciplinary applications and evaluation of computer architectures and software environments.
Download or read book Aeronautical Engineering written by and published by . This book was released on 1993 with total page 722 pages. Available in PDF, EPUB and Kindle. Book excerpt: A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA)
Download or read book Tenth Australasian Fluid Mechanics Conference written by and published by . This book was released on 1989 with total page 414 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 1989 with total page 1708 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Annual Research Briefs 1994 written by Center for Turbulence Research (U.S.) and published by . This book was released on 1994 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Annual Research Briefs 1994 written by and published by . This book was released on 1994 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aeronautical Engineering A Cumulative Index to a Continuing Bibliography supplement 235 written by and published by . This book was released on 1989 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:
