Download or read book A Numerical Study of Viscous Vortex Rings Using a Spectral Method written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-17 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Viscous, axisymmetric vortex rings are investigated numerically by solving the incompressible Navier-Stokes equations using a spectral method designed for this type of flow. The results presented are axisymmetric, but the method is developed to be naturally extended to three dimensions. The spectral method relies on divergence-free basis functions. The basis functions are formed in spherical coordinates using Vector Spherical Harmonics in the angular directions, and Jacobi polynomials together with a mapping in the radial direction. Simulations are performed of a single ring over a wide range of Reynolds numbers (Re approximately equal gamma/nu), 0.001 less than or equal to 1000, and of two interacting rings. At large times, regardless of the early history of the vortex ring, it is observed that the flow approaches a Stokes solution that depends only on the total hydrodynamic impulse, which is conserved for all time. At small times, from an infinitely thin ring, the propagation speeds of vortex rings of varying Re are computed and comparisons are made with the asymptotic theory by Saffman. The results are in agreement with the theory; furthermore, the error is found to be smaller than Saffman's own estimate by a factor square root ((nu x t)/R squared) (at least for Re=0). The error also decreases with increasing Re at fixed core-to-ring radius ratio, and appears to be independent of Re as Re approaches infinity). Following a single ring, with Re=500, the vorticity contours indicate shedding of vorticity into the wake and a settling of an initially circular core to a more elliptical shape, similar to Norbury's steady inviscid vortices. Finally, we consider the case of leapfrogging vortex rings with Re=1000. The results show severe straining of the inner vortex core in the first pass and merging of the two cores during the second pass. Stanaway, S. K. and Cantwell, B. J. and Spalart, Philippe R. Ames Research Center COMPUTATIONAL FLUID DYNAMICS; NAVIER-STOKES EQUATION...
Download or read book A Numerical Study of Viscous Vortex Rings Using a Spectral Method written by Sharon K. Stanaway and published by . This book was released on 1988 with total page 348 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 1995 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Vortex Flows and Related Numerical Methods written by J.T. Beale and published by Springer Science & Business Media. This book was released on 2013-04-18 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many important phenomena in fluid motion are evident in vortex flow, i.e., flows in which vortical structures are significant in determining the whole flow. This book, which consists of lectures given at a NATO ARW held in Grenoble (France) in June 1992, provides an up-to-date account of current research in the study of these phenomena by means of numerical methods and mathematical modelling. Such methods include Eulerian methods (finite difference, spectral and wavelet methods) as well as Lagrangian methods (contour dynamics, vortex methods) and are used to study such topics as 2- or 3-dimensional turbulence, vorticity generation by solid bodies, shear layers and vortex sheets, and vortex reconnection. For researchers and graduate students in computational fluid dynamics, numerical analysis, and applied mathematics.
Download or read book Studying Turbulence Using Numerical Simulation Databases II written by Center for Turbulence Research (U.S.) and published by . This book was released on 1988 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aerodynamics And Aeroacoustics Proceedings Of The Symposium written by Fung K Y and published by World Scientific. This book was released on 1994-04-19 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of the symposium was to gather fellow researchers, colleagues and friends of Professor William R Sears, a member of the National Academy of Science and the Academy of Engineering, on the occasion of his 80th birthday. Professor Sears is a leader in Aerospace Science and Aerodynamics research and the symposium was held in honour of his work in these areas.The symposium focussed on four areas in aeronautical science in which Professor Sears has made major contributions. These are wing design, unsteady aerodynamics and separation, aeroacoustics and self-correcting wind tunnels.
Download or read book Monthly Catalogue United States Public Documents written by and published by . This book was released on 1992 with total page 1384 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monthly Catalog of United States Government Publications written by and published by . This book was released on with total page 1112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulation of Incompressible Pipe Flow Using a B spline Spectral Method written by Patrick Loulou and published by . This book was released on 1996 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances In Engineering Mechanics reflections And Outlooks In Honor Of Theodore Y t Wu written by Daniel T Valentine and published by World Scientific. This book was released on 2005-11-29 with total page 747 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents more than 40 original papers on recent advances in several topics in engineering mechanics presented at The Theodore Y-T Wu Symposium on Engineering Mechanics: A celebration of Professor Wu's scientific contributions for his 80th birthday. The distinguished contributors include several members of the National Academy of Engineers and the topics cover nonlinear water waves, swimming and flying in nature, biomechanics, data analysis methodology, and propulsion hydrodynamics.The papers honor the significant accomplishments of Professor Wu in Engineering Science at Caltech, particularly in the areas of nonlinear waves, hydrodynamics, biomechanics and wave-structure interaction. They review the present state of the art of engineering mechanics, and chart the future of the field from the viewpoint of civil engineering, biomechanics, geophysics, mechanical engineering, naval architecture, ocean, and offshore engineering. The primary purpose of this book is to provide guidance and inspiration for those interested in continuing to advance engineering mechanics into the 21st century. To quote Professor Wu: ”The value of a book publication lies in disseminating new knowledge attained with effort and dedication from all those who participate, and in having the useful results within ready reach of students and researchers actively working in the field.”
Download or read book Combined Experimental and Numerical Investigations of a Vortex Ring Impinging Normally on a Wall written by Dražen Fabris and published by . This book was released on 1996 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Simulation and Modeling of Turbulent Flows written by T. B. Gatski and published by Oxford University Press, USA. This book was released on 1996 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides students and researchers in fluid engineering with an up-to-date overview of turbulent flow research in the areas of simulation and modeling. A key element of the book is the systematic, rational development of turbulence closure models and related aspects of modern turbulent flow theory and prediction. Starting with a review of the spectral dynamics of homogenous and inhomogeneous turbulent flows, succeeding chapters deal with numerical simulation techniques, renormalization group methods and turbulent closure modeling. Each chapter is authored by recognized leaders in their respective fields, and each provides a thorough and cohesive treatment of the subject.
Download or read book Aeronautical Engineering written by and published by . This book was released on 1992 with total page 648 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 Government Reports Annual Index written by and published by . This book was released on 1989 with total page 1372 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Vortex Ring Models written by Ionut Danaila and published by Springer Nature. This book was released on 2021-04-16 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a guide to understanding models of vortex rings, starting from classical ones (circular vortex filament, Hill and Norbury-Fraenkel inviscid models) to very recent models incorporating viscous effects and realistic shapes of the vortex core. Unconfined and confined viscous vortex rings are described by closed formulae for vorticity, stream function, translational velocity, energy, impulse and circulation. Models are applied to predict the formation number of optimal vortex rings and to describe two-phase vortex ring-like structures generated in internal combustion engines. The book provides a detailed presentation of analytical developments of models, backed up by illustrations and systematic comparisons with results of direct numerical simulations. The book is useful for graduate students in applied mathematics, engineering and physical sciences. It is a useful reference for researchers and practising engineers interested in modelling flows with vortex rings.
Download or read book Vortex Methods written by Georges-Henri Cottet and published by Cambridge University Press. This book was released on 2008-04-24 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vortex methods have matured in recent years, offering an interesting alternative to finite difference and spectral methods for high resolution numerical solutions of the Navier Stokes equations. In the past three decades, research into the numerical analysis aspects of vortex methods has provided a solid mathematical background for understanding the accuracy and stability of the method. At the same time vortex methods retain their appealing physical character, which was the motivation for their introduction. This book presents and analyzes vortex methods as a tool for the direct numerical simulation of impressible viscous flows. It will interest graduate students and researchers in numerical analysis and fluid mechanics and also serve as an ideal textbook for courses in fluid dynamics.
Download or read book Fluid Flow Phenomena written by Paolo Orlandi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with the simulation of the incompressible Navier-Stokes equations for laminar and turbulent flows. The book is limited to explaining and employing the finite difference method. It furnishes a large number of source codes which permit to play with the Navier-Stokes equations and to understand the complex physics related to fluid mechanics. Numerical simulations are useful tools to understand the complexity of the flows, which often is difficult to derive from laboratory experiments. This book, then, can be very useful to scholars doing laboratory experiments, since they often do not have extra time to study the large variety of numerical methods; furthermore they cannot spend more time in transferring one of the methods into a computer language. By means of numerical simulations, for example, insights into the vorticity field can be obtained which are difficult to obtain by measurements. This book can be used by graduate as well as undergraduate students while reading books on theoretical fluid mechanics; it teaches how to simulate the dynamics of flow fields on personal computers. This will provide a better way of understanding the theory. Two chapters on Large Eddy Simulations have been included, since this is a methodology that in the near future will allow more universal turbulence models for practical applications. The direct simulation of the Navier-Stokes equations (DNS) is simple by finite-differences, that are satisfactory to reproduce the dynamics of turbulent flows. A large part of the book is devoted to the study of homogeneous and wall turbulent flows. In the second chapter the elementary concept of finite difference is given to solve parabolic and elliptical partial differential equations. In successive chapters the 1D, 2D, and 3D Navier-Stokes equations are solved in Cartesian and cylindrical coordinates. Finally, Large Eddy Simulations are performed to check the importance of the subgrid scale models. Results for turbulent and laminar flows are discussed, with particular emphasis on vortex dynamics. This volume will be of interest to graduate students and researchers wanting to compare experiments and numerical simulations, and to workers in the mechanical and aeronautic industries.
