Vortex Stability and Breakdown

Vortex Stability and Breakdown PDF Author: S. Leibovich
Publisher:
ISBN:
Category :
Languages : en
Pages : 22

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Book Description
Theoretical and experimental results, some quite recent, on the instability and breakdown of concentrated vortices at high Reynolds numbers are reviewed. Wave related theories of the vortex breakdown phenomena are treated in some detail; these appear to provide a qualitative description of the response of vortex breakdown to variations in swirl or flow rate, and Benjamin's criticality classification, a wave-based concept, is consistent with experimental data. Known general criteria for the stability of instability of inviscid columnar vortices are reviewed, together with numerical studies of an inviscid vortex model that provides an excellent analytical fit to measured velocity profiles in vortices that experience breakdown. A new analysis of experimental data on vortex breakdown flows sheds light on the interplay between criticality and instability. The flows sufficiently far upstream of breakdowns to be unaffected by them are supercritical and stable, but they are generally closer to marginal instability than they are to criticality. The wakes are both subcritical and unstable. A conceptual framework for vortex breakdown, incorporating nonlinear wave theory and instability to three-dimensional disturbances, is suggested based on information derived from the experimental studies. (Author).

Vortex Stability and Breakdown

Vortex Stability and Breakdown PDF Author: S. Leibovich
Publisher:
ISBN:
Category :
Languages : en
Pages : 22

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Book Description
Theoretical and experimental results, some quite recent, on the instability and breakdown of concentrated vortices at high Reynolds numbers are reviewed. Wave related theories of the vortex breakdown phenomena are treated in some detail; these appear to provide a qualitative description of the response of vortex breakdown to variations in swirl or flow rate, and Benjamin's criticality classification, a wave-based concept, is consistent with experimental data. Known general criteria for the stability of instability of inviscid columnar vortices are reviewed, together with numerical studies of an inviscid vortex model that provides an excellent analytical fit to measured velocity profiles in vortices that experience breakdown. A new analysis of experimental data on vortex breakdown flows sheds light on the interplay between criticality and instability. The flows sufficiently far upstream of breakdowns to be unaffected by them are supercritical and stable, but they are generally closer to marginal instability than they are to criticality. The wakes are both subcritical and unstable. A conceptual framework for vortex breakdown, incorporating nonlinear wave theory and instability to three-dimensional disturbances, is suggested based on information derived from the experimental studies. (Author).

Vorticity and Vortex Dynamics

Vorticity and Vortex Dynamics PDF Author: Jie-Zhi Wu
Publisher: Springer Science & Business Media
ISBN: 3540290281
Category : Technology & Engineering
Languages : en
Pages : 776

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Book Description
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.

Vortex stability and breakdown

Vortex stability and breakdown PDF Author: Michael Stuart Broadhurst
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description


On Vortex Breakdown and Instability

On Vortex Breakdown and Instability PDF Author: S. N. Singh
Publisher:
ISBN:
Category : Axial flow
Languages : en
Pages : 72

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Book Description
A literature survey on the vortex breakdown phenomenon is presented. Several theoretical and numerical models which have been proposed and applied to explain the experimental observations concerning vortex bursting are reviewed. Required parameters to perform the related stability analysis have been identified. Appropriate criteria where possible are cited to assist engineers in estimating occurrence of vortext bursting. A numerical scheme to compute and verify some of the results for incompressible inviscid unstable modes is programmed on the computer at WPAFB. It is suggested that the influence of adverse pressure gradient on the vortex breakdown be investigated in detail and results thus obtained be compared with experiments under appropriate conditions.

Fluid Vortices

Fluid Vortices PDF Author: Sheldon Green
Publisher: Springer Science & Business Media
ISBN: 940110249X
Category : Technology & Engineering
Languages : en
Pages : 905

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Book Description
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.

An Investigation of Vortex Breakdown from the Point of View of Hydrodynamic Stability

An Investigation of Vortex Breakdown from the Point of View of Hydrodynamic Stability PDF Author: Thinh Tien Nguyen
Publisher:
ISBN:
Category : Hydrodynamics
Languages : en
Pages : 296

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Book Description


Explanation of Vortex Breakdown with the Help of Stability Theory of Spiralling Flows

Explanation of Vortex Breakdown with the Help of Stability Theory of Spiralling Flows PDF Author: Hubert Ludwieg
Publisher:
ISBN:
Category : Vortex-motion
Languages : en
Pages : 40

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Book Description


Calculations of the Stability of Some Axisymmetric Flows Proposed as a Model of Vortex Breakdown

Calculations of the Stability of Some Axisymmetric Flows Proposed as a Model of Vortex Breakdown PDF Author: Nessan Mac Giolla Mhuiris
Publisher:
ISBN:
Category :
Languages : en
Pages : 48

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Book Description


Theory of Concentrated Vortices

Theory of Concentrated Vortices PDF Author: S. V. Alekseenko
Publisher: Springer Science & Business Media
ISBN: 3540733760
Category : Technology & Engineering
Languages : en
Pages : 505

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Book Description
This book presents comprehensive and authoritative coverage of the wide field of concentrated vortices observed in nature and technique. The methods for research of their kinematics and dynamics are considered. Special attention is paid to the flows with helical symmetry. The authors have described models of vortex structures used for interpretation of experimental data which serve as a ground for development of theoretical and numerical approaches to vortex investigation.

On Vortex Breakdown and Instability

On Vortex Breakdown and Instability PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
A literature survey on the vortex breakdown phenomenon is presented. Several theoretical and numerical models which have been proposed and applied to explain the experimental observations concerning vortex bursting are reviewed. Required parameters to perform the related stability analysis have been identified. Appropriate criteria where possible are cited to assist engineers in estimating occurrence of vortex bursting. A numerical scheme to compute and verify some of the results for incompressible inviscid unstable modes is programmed on the computer at WPAFB. It is suggested that the influence of adverse pressure gradient on the vortex breakdown be investigated in detail and results thus obtained be compared with experiments under appropriate conditions. (Author).