Numerical Simulation of Vortex Breakdown by the Vortex-filament Method

Numerical Simulation of Vortex Breakdown by the Vortex-filament Method
Author: Y. Nakamura
Publisher:
Total Pages: 20
Release: 1983
Genre: Numerical analysis
ISBN:

The vortex-filament method was applied to the simulation of vortex breakdown. The principal vortex region was represented by multiple filaments, and an axial velocity component was induced by a spiral winding of the filaments. First, an accuracy check was performed for a cylindrical swirling flow field that can be simulated to any accuracy by increasing the number of filaments. Second, an axisymmetric-type vortex breakdown was simulated, with experimental data serving asupstream conditions. The calculated axial- and theta-velocity contours show the breakdown of the vortex, including a rapid change in the vortex core, followed axially by a recovery zone and then a second breakdown. When three-dimensional initial data are used the second breakdown appears to be out of the spiral type in correspondence with experimental observations. The present method can easily be used to simulate other types of vortex breakdown or other vortex flows with axial velocity.

Vortex Dominated Flows

Vortex Dominated Flows
Author: Lu Ting
Publisher: World Scientific
Total Pages: 302
Release: 2005
Genre: Science
ISBN: 9812703438

Honoring the contributions of one of the field''s leading experts, Lu Ting, this indispensable volume contains important new results at the cutting edge of research. A wide variety of significant new analytical and numerical results in critical areas are presented, including point vortex dynamics, superconductor vortices, cavity flows, vortex breakdown, shock/vortex interaction, wake flows, magneto-hydrodynamics, rotary wake flows, and hypersonic vortex phenomena. The book will be invaluable for those interested in the state of the art of vortex dominated flows, both from a theoretical and applied perspective. Professor Lu Ting and Joe Keller have worked together for over 40 years. In their first joint work entitled OC Periodic vibrations of systems governed by nonlinear partial differential equationsOCO, perturbation analysis and bifurcation theory were used to determine the frequencies and modes of vibration of various physical systems. The novelty was the application to partial differential equations of methods which, previously, had been used almost exclusively on ordinary differential equations. Professsor Lu Ting is an expert in both fluid dynamics and the use of matched asymptotic expansions. His physical insight into fluid flows has led the way to finding the appropriate mathematical simplications used in the solutions to many difficult flow problems."

Fluid Vortices

Fluid Vortices
Author: Sheldon Green
Publisher: Springer Science & Business Media
Total Pages: 905
Release: 2012-12-06
Genre: Technology & Engineering
ISBN: 940110249X

Fluid Vortices is a comprehensive, up-to-date, research-level overview covering all salient flows in which fluid vortices play a significant role. The various chapters have been written by specialists from North America, Europe and Asia, making for unsurpassed depth and breadth of coverage. Topics addressed include fundamental vortex flows (mixing layer vortices, vortex rings, wake vortices, vortex stability, etc.), industrial and environmental vortex flows (aero-propulsion system vortices, vortex-structure interaction, atmospheric vortices, computational methods with vortices, etc.), and multiphase vortex flows (free-surface effects, vortex cavitation, and bubble and particle interactions with vortices). The book can also be recommended as an advanced graduate-level supplementary textbook. The first nine chapters of the book are suitable for a one-term course; chapters 10--19 form the basis for a second one-term course.

NASA SP.

NASA SP.
Author:
Publisher:
Total Pages: 590
Release: 1993
Genre: Aeronautics
ISBN:

General Momentum Theory for Horizontal Axis Wind Turbines

General Momentum Theory for Horizontal Axis Wind Turbines
Author: Jens Nørkær Sørensen
Publisher: Springer
Total Pages: 203
Release: 2015-08-17
Genre: Technology & Engineering
ISBN: 3319221140

This book reconsiders the basic approaches behind the BEM method and in particular assesses and validates the equations forming the general momentum theory. One part of the book concerns the validation, using numerical fluid mechanics (CFD), of the different terms in the equations forming the momentum theory. Other parts present new ideas for extending the theory and for enhancing the accuracy of the BEM approach. Besides a general introduction and explanation of the momentum theory, the book also deals with specialized topics, such as diffusor-augmented rotors, wind tunnel corrections, tip corrections, and combined momentum/vortex theory for design of wind turbine rotors. The book contains new as well as already published material, and the author has strived to put the material into a new and more consistent context than what usually is found in similar text books. The book is primarily intended for researchers and experienced students with a basic knowledge in fluid mechanics wishing to understand and expand their knowledge on wind turbine aerodynamics. The book is self-consistent, hence all necessary derivations are shown, and it should not be necessary to seek help in other literature to understand the contents of the book.

Vorticity and Vortex Dynamics

Vorticity and Vortex Dynamics
Author: Jie-Zhi Wu
Publisher: Springer Science & Business Media
Total Pages: 776
Release: 2007-04-20
Genre: Technology & Engineering
ISBN: 3540290281

This book is a comprehensive and intensive monograph for scientists, engineers and applied mathematicians, as well as graduate students in fluid dynamics. It starts with a brief review of fundamentals of fluid dynamics, with an innovative emphasis on the intrinsic orthogonal decomposition of fluid dynamic process, by which one naturally identifies the content and scope of vorticity and vortex dynamics. This is followed by a detailed presentation of vorticity dynamics as the basis of later development. In vortex dynamics part the book deals with the formation, motion, interaction, stability, and breakdown of various vortices. Typical vortex structures are analyzed in laminar, transitional, and turbulent flows, including stratified and rotational fluids. Physical understanding of vertical flow phenomena and mechanisms is the first priority throughout the book. To make the book self-contained, some mathematical background is briefly presented in the main text, but major prerequisites are systematically given in appendices. Material usually not seen in books on vortex dynamics is included, such as geophysical vortex dynamics, aerodynamic vortical flow diagnostics and management.