Download or read book Bifurcating Jets at High Reynolds Numbers written by D. E. Parekh and published by . This book was released on 1988 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is much interest in the use of controlled excitations to manage various types of flows. This work focuses on use of dual-mode forcing to alter dramatically the structure of round turbulent jets. Properly-combined axial and helical excitations can cause a round jet to split into two distinct jets. This Y-shaped jet, known as a bifurcating jet, exhibits spreading angles as high as 80 deg. Vortex rings are formed at the jet exit and propagate along the two branches of the jet. A vortex-filament code was developed for simulating the large-scale features of bifurcating jets. The motion and interaction of the vortex structures in this flow are tracked in a three-dimensional, Lagrangian coordinate system. This simulation showed that inviscid vortex interactions cause the dramatic changes in jet development and that spreading angle increases with axial Strouhal number. The experimental apparatus consists of an acoustically-excited, 2-cm-diameter air jet. The jet evolution is documented by flow visualization at velocities up to 75 m/s, Reynolds numbers up to 100,000, and Mach numbers up to 0.22. Instantaneous and phase-average cross-sections of the jet reveal the effects of forcing amplitude on the structure and spreading angle of axially-excited, helically-excited, and bifurcating jets. The primary conclusions of this experiment are that: 1) Dual-mode acoustic excitation can produce bifurcation in air jets at high Reynolds numbers and that the jet spreading angle increases with both excitation amplitudes; and 2) The excitation amplitude required to produce bifurcation increases with Reynolds number, but the corresponding excitation Strouhal number is invariant. (EDC).
Download or read book Bifurcating and Blooming Jets written by Mario Lee and published by . This book was released on 1985 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Control of Structure in Turbulent Flows Bifurcating and Blooming Jets written by W. C. Reynolds and published by . This book was released on 1987 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: The general objective of this work is to control jet flows by properly organizing the dominant large-scale vortex structures. The work has focused on understanding the influence of excitation frequency and amplitude on the large-scale structures of these flows at various Reynolds numbers. Specifically, the effects of dual-mode forcing on the structure, momentum, and mixing characteristics of turbulent jets have been investigated using a combination of laboratory experiments and numerical simulations. The combination of properly-selected axial and orbital excitation has been shown to have dramatic effect on the structure and mixing of round jets. Experiments and numerical simulations show that these phenomena are due to interaction between the large-scale vortices in the jet near field. The position and phasing of these vortices can be altered by relatively weak excitation, causing the jet to divide into two separate jets (bifurcation) or to explode (bloom) in a shower of vortex rings. This report summarizes the key results of studies in water and low-speed air flows.
Download or read book Manipulation and Control of Jets in Crossflow written by Ann R. Karagozian and published by Springer. This book was released on 2014-05-04 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamental Non-Reactive Jets in Crossflow and Other Jet Systems; Background on Modeling, Dynamical Systems, and Control; Reactive Jets in Crossflow and Multiphase Jets; Controlled Jets in Crossflow and Control via Jet Systems;
Download or read book Control of High Reynolds Number Round Jets written by Philippe Jean-Daniel Juvet and published by . This book was released on 1993 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Global Geometry of Turbulence written by Javier Jiménez and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this Advanced Research Workshop was to bring together Physicists, Applied Mathematicians and Fluid Dynamicists, including very specially experimentalists, to review the available knowledge on the global structural aspects of turbulent flows, with an especial emphasis on open systems, and to try to reach a consensus on their possible relationship to recent advances in the understanding of the behaviour of low dimensional dynamical systems and amplitude equations. A lot has been learned during recent years on the non-equilibrium behaviour of low dimen sional dynamical systems, including some fluid flows (Rayleigh-Benard, Taylor-Couette, etc. ). These are mostly closed flows and many of the global structural features of the low dimensional systems have been observed in them, including chaotic behaviour, period doubling, intermit tency, etc. . It has also been shown that some of these flows are intrinsically low dimensional, which accounts for much of the observed similarities. Open flows seem to be different, and experimental observations point to an intrinsic high dimensionality. However, some of the tran sitional features of the low dimensional systems have been observed in them, specially in the intermittent behaviour of subcritical flows (pipes, channels, boundary layers with suction, etc. ), and in the large scale geometry of coherent structures of free shear flows (mixing layers, jets and wakes).
Download or read book Large Eddy Simulations of Turbulence written by M. Lesieur and published by Cambridge University Press. This book was released on 2005-08-22 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large-Eddy Simulations of Turbulence is a reference for LES, direct numerical simulation and Reynolds-averaged Navier-Stokes simulation.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transition Turbulence and Combustion Modelling written by A. Hanifi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: This single-volume work gives an introduction to the fields of transition, turbulence, and combustion modeling of compressible flows and provides the physical background for today’s modeling approaches in these fields. It presents basic equations and discusses fundamental aspects of hydrodynamical instability.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1976 with total page 990 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct and Large Eddy Simulation VII written by Vincenzo Armenio and published by Springer Science & Business Media. This book was released on 2010-04-28 with total page 575 pages. Available in PDF, EPUB and Kindle. Book excerpt: After Surrey in 1994, Grenoble in 1996, Cambridge in 1999, Enschede in 2001, Munich in 2003 and Poiters in 2005, the 7th Workshop, DLES7, will be held in Trieste, again under the auspices of ERCOFTAC. Following the spirit of the series, the goal of this latest workshop is to establish a state-of-the-art of DNS and LES techniques for the computation and modeling of transitional/turbulent flows covering a broad scope of topics such as aerodynamics, acoustics, combustion, multiphase flows, environment, geophysics and bio-medical applications. This gathering of specialists in the field should once again be a unique opportunity for discussions about the more recent advances in the prediction, understanding and control of turbulent flows in academic or industrial situations.
Download or read book Experimental Heat Transfer Fluid Mechanics and Thermodynamics 1993 written by M.D. Kelleher and published by Elsevier. This book was released on 2012-12-02 with total page 1002 pages. Available in PDF, EPUB and Kindle. Book excerpt: The papers contained in this volume reflect the ingenuity and originality of experimental work in the areas of fluid mechanics, heat transfer and thermodynamics. The contributors are drawn from 27 countries which indicates how well the worldwide scientific community is networked. The papers cover a broad spectrum from the experimental investigation of complex fundamental physical phenomena to the study of practical devices and applications. A uniform outline and method of presentation has been used for each paper.
Download or read book Direct and Large Eddy Simulation VI written by E. Lamballais and published by Springer Science & Business Media. This book was released on 2006-10-19 with total page 783 pages. Available in PDF, EPUB and Kindle. Book excerpt: The sixth ERCOFTAC Workshop on ‘Direct and Large-Eddy Simulation’ (DLES-6) was held at the University of Poitiers from September 12-14, 2005. Following the tradition of previous workshops in the DLES-series, this edition has reflected the state-of-the-art of numerical simulation of transitional and turbulent flows and provided an active forum for discussion of recent developments in simulation techniques and understanding of flow physics.
Download or read book Direct and Large Eddy Simulation IV written by Bernard Geurts and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the proceedings of the 2001 DLES4 workshop. It describes and discusses state-of-the-art modeling and simulation approaches for complex flows. Fundamental turbulence and modeling issues but also elements from modern numerical analysis are at the heart of this field of interest.
Download or read book Fundamental Problematic Issues in Turbulence written by Albert Gyr and published by Birkhäuser. This book was released on 2012-12-06 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: A collection of contributions on a variety of mathematical, physical and engineering subjects related to turbulence. Topics include mathematical issues, control and related problems, observational aspects, two- and quasi-two-dimensional flows, basic aspects of turbulence modeling, statistical issues and passive scalars.
Download or read book Separated Flows and Jets written by Victor V. Kozlov and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 907 pages. Available in PDF, EPUB and Kindle. Book excerpt: Separated flows and jets are closely linked in a variety of applications. They are of great importance in various fields of fluid mechanics including vehicle efficiency, technical branches concerned with gas/liquid flows, atmospheric effects on various constructions, etc. Knowledge of the physics of separated flows and jets and the development of reliable control techniques are prerequisite for future progress in the field. These aspects were in focus during the IUTAM-Symposium which was held in Novosibirsk, 9-13 July, 1990. This volume contains a selection of papers presenting recent results of theoretical and numerical studies as well as experimental work on separated flows and jets. The topics include sub- and supersonic, laminar and turbulent separation as well as organized structures in separated flows and jets. The reader will find here the state of the art and major trends for research in this field of aero-hydrodynamics.
Download or read book Reynolds Number Dependence of the Neutrally Buoyant Turbulent Round Jet written by Gustavo Zarruk and published by . This book was released on 2002 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
