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3 edition of Evolution of hairpin vortices in a shear flow found in the catalog.

Evolution of hairpin vortices in a shear flow

Evolution of hairpin vortices in a shear flow

  • 75 Want to read
  • 36 Currently reading

Published by National Aeronautics and Space Administration, For sale by the National Technical Information Service in [Washington, D.C.], [Springfield, Va .
Written in English

    Subjects:
  • Shear flow.,
  • Fluid mechanics.

  • Edition Notes

    StatementT -L. Hon and J.D.A. Walker.
    SeriesNASA technical memorandum -- 100858.
    ContributionsWalker, J. D. A., United States. National Aeronautics and Space Administration.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL14663271M

    Full text of "DTIC ADA Proceedings of the International Symposium on Seawater Drag Reduction, July Newport, Rhode Island" See other formats.   On hairpin vortex generation from near-wall streamwise vortices. NASA Astrophysics Data System (ADS) Wang, Yinshan; Huang, Weixi; Xu, Chunxiao. The generation of a hairpin vortex from near-wall streamwise vortices is studied via the direct numerical simulation (DNS) of the streak transient growth in the minimal channel flow at. The streak profile is obtained by . Password requirements: 6 to 30 characters long; ASCII characters only (characters found on a standard US keyboard); must contain at least 4 different symbols;. Hairpin vortices that occur far from the wall, such as those labelled AC in figure 9(a) may not possess quasistreamwise vortex legs, being instead more similar to those seen in homogeneous turbulent shear flow (Adrian & Moin ). 5. Structure in the outer region


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Evolution of hairpin vortices in a shear flow Download PDF EPUB FB2

Hairpin vortices were generated at the surface of the inner cylinder of an axisymmetric Couette apparatus, using suction through two holes. An instability domain, within the range of the basic flow parameters where the flow is known to be linearly stable, was : Edwin Malkiel, Vladimir Levinski, Moshe Rosenfeld, Jacob Cohen.

The evolution of artificially generated localized disturbances in the shape of hairpin vortices, in laminar axisymmetric rotating shear flows, is investigated experimentally.

Get this from a library. Evolution of hairpin vortices in a shear flow. [T L Hon; J D A Walker; United States. National Aeronautics and Space Administration.].

Although it is not possible to track the evolution of hairpins over long periods, it is possible to identify and trace their evolution over short time periods.

Some of the key notable features of hairpin vortices are how they interact with the background shear flow, other vortices. The effect of a shear-thinning fluid governed by a power-law model on the evolution of a hairpin vortex in a wall-bounded flow was studied by means of direct numerical simulation.

In particular, the following topics are of interest: (1) the nature of the evolution of hairpin vortices in a shear flow; (2) the type of flow induced near a wall by a convected hairpin vortex; (3) the character of the viscous response near a wall to the hairpin vortex motion.

Turbulence stands as one of the most complicated and attractive physical phenomena. The accumulated knowledge has shown turbulent flow to be composed of islands of vortices and uniform-momentum regions, which are coherent in both time and space.

Research has been concentrated on these structures, their generation, evolution, and interaction with the mean : Zambri Harun, Eslam Reda Lotfy. The paper discusses the development of single hairpin vortices, how such vortices interact with a shear flow and with one another, and how they interact with the flow near a wall to produce new vortices through a viscous by: In particular, the following topics are of interest: (1) the nature of the evolution of hairpin vortices in a shear flow; (2) the type of flow induced near a wall by a convected hairpin vortex; (3) the character of the viscous response near a wall to the hairpin vortex motion and (4) the nature of themore».

() Evolution of hairpin vortices in a shear flow. Computers & Fluids() Three-dimensional distortions of a vortex filament with axial by: It is generally accepted that the key features in this regard are vortices variously called horseshoe vortices or hairpin vortices, owing to their characteristic shape (Figures \(\PageIndex{3}\), \(\PageIndex{4}\)).

These vortices develop, in ways not yet well understood, and then become stretched downstream by the strong mean shear, and as.

The flow of a viscous fluid in a plane channel is simulated numerically following the DNS approach, and using a computational code for the numerical integration of the Navier-Stokes equations implemented on a hybrid CPU/GPU computing architecture (for the meaning of symbols and acronyms used, one can refer to the Nomenclature).

Three turbulent-flow databases, each representing the turbulent Cited by: 1. The Relationship between Streaks and Hairpin Vortices in Subcritical Wall Bounded Shear Flows: Braun Benyamin Orit: PhD: Experimental Study of the Evolution of the Coherent Structures in Wall Bounded Shear Flows Using HPIV: Amitay Michael: Formation and Evolution of Buoyancy Driven Vortices in Stratified Shear Flow: Vyomesh Mehta.

Instability and Breakdown of the Three-Dimensional High-Shear Layer Associated with a Near-Wall Low-Speed Streak.- On Vortex Interaction in the Latter Stages of Boundary-Layer Transition.- The Evolution of Hairpin Vortices in Shear Flows We review the progress on the theory and applications of the vortex-surface field (VSF).

The VSF provides a systematic Lagrangian-based framework for the identification, characterization, and modeling of flow structures. From the theoretical perspective, the vorticity is simplified to a scalar field as the VSF.

The VSF isosurface is a vortex surface consisting of vortex : Yue Yang. Haidari and Smith () observed two scenarios: one in which the single hairpin would, "remain a single vortex, generally decaying without displaying growth of the overal flow structureˮ, and another where it would, "stimulate the development of ancillary hairpin vortices, causing the overall flow structure to continually grow and by: American Institute of Aeronautics and Astronautics Sunrise Valley Drive, Suite Reston, VA A turbulent horseshoe vortex (HV) system around a wall-mounted cylinder in open channel is characterized by random variations in vortex features and an abundance of vortex interactions.

The turbulent HV system is responsible for initiating the local scour process in front of the cylinder. The evolution of the turbulent HV system is investigated statistically and quantitatively with time Author: Qigang Chen, Zuolei Yang, Haojie Wu.

The three-dimensional structure of momentum transfer in turbulent channels - Volume - Adrián Lozano-Durán, Oscar Flores, Javier Jiménez Book chapters will be unavailable on Saturday 24th August between 8ampm by:   The basic structures in a turbulent boundary layer are hairpin, pocket, and flow direction vortices, as well as typical eddies; the composite structures are low-speed streaks, hairpin vortex packets, turbulent spots, very-large-scale motions (VLSM), and superstructures.

The First Symposium on Turbulence and Shear Flow Phenomena was held Septemberin Santa Barbara, California. This new symposium series is the successor to the highly regarded series of Symposia on Turbulent Shear Flows, which concluded with the 11th biennial conference in The Symposium aims to be the premier forum for presentation of fundamental and applied research in.

It was widely accepted that the last stage of laminar flow transition is caused by “hairpin vortex breakdown”. Fig. 12 shows a schematic of flow transition on a flat plate in the book by Schlichting and Gersten. However, the hairpin structure is pretty stable and Cited by: 3d kolmogorov-type flow nick evstigneev 26 the emergence of hairpin vortices from exact coherent sttesa in plane poiseuille flow m.

arfano, p. de palma, j.-c. robinet, s. cherubini and t. schneider 27 "smart" assivep thermal insulation of confined natural convection heat transfer: an application to hollow construction blocks shaharFile Size: 8MB. The evolution of a single hairpin vortex-like structure in the mean turbulent field of a low-Reynolds-number channel flow is studied by direct numerical simulation.

The structure of the initial three-dimensional vortex is extracted from the two-point spatial correlation of the velocity field by linear stochastic estimation given a second.

These vortices are generated by entertainment and reorientation of the boundary layer into the wake region. Hairpin vortices. Like any fully turbulent boundary layer flow, for the case of attached jets, the far field of the coolant jet is characterized by hairpin vortices and three-dimensional turbulent structures.

Ghaemi S. & Scarano F. Counter-hairpin vortices in the turbulent wake of a sharp trailing edge, Journal of Fluid Mechanicspp. Kotsonis M. & Ghaemi S. Forcing mechanisms of dielectric barrier discharge plasma actuators at carrier frequency of Hz, Journal of Applied Physics, (11), art.

Some new ideas on the dynamics of shear flow turbulence are presented. Central to these is the phenomenon of wave breakdown. This is defined as the onset of a violent small-scale secondary instability developing on a large-scale primary disturbance of wave-like traveling type.

It is suggested that breakdown together with the ensuing violent mixing process (a turbulent “burst”) constitutes Cited by:   Dutton (, –) showed from an integral of the vector vorticity equation that absolute vorticity ω in dry, inviscid, isentropic flows is the sum of barotropic and baroclinic components, ω BT and ω BC, decomposition is dependent on the arbitrary choice of the initial time, t = 0.

The barotropic vorticity at a subsequent (or “current”) time t is the vorticity Cited by: Our first approach to prepare initial vortices is to extract the vortices produced from Scenario 1 and take them to create the initial condition before evolution. Specifically, we take a volume of data from the previous simulation result as Φ 0, and set Φ 1 according to Eq.

14, where ω 0 is tweaked to be compatible with other parameters. The. A large eddy simulation (LES) was conducted to investigate the separated flow transition on the suction surface of a high subsonic compressor airfoil at two Reynolds number (Re) conditions ( × 10 5 and × 10 5).The detailed vortex evolution in the separated shear layer was revealed.

and sustenance since a conceptual model of hairpin vortex was proposed by Theodorsen. 5 Several important coherent structures have been identified, including vortex “worms” in isotropic turbulence,6,7 hairpin vortices in wall-bounded turbulence, quasi-streamwise vortices 4,11,12 and Author: Yisheng Gao, Chaoqun Liu.

[1] We describe and compare idealized high‐resolution simulations of turbulence arising due to Kelvin‐Helmholtz shear instability and gravity‐wave breaking, believed to be t.

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.

An experimental study was conducted to explore the effect of surface flexibility at the leading and trailing edges on the near-wake flow dynamics of a sinusoidal heaving foil.

Midspan particle image velocimetry (PIV) measurements were taken in a closed-loop wind tunnel at a Reynolds number of 25, and at a range of reduced frequencies (k = fc Cited by: 9. Want more fluidsy goodness.

Take a trip through our archive. By Date By Category By Topic Feeling Random. Don’t know what you want. Then by all means, press the button. Still having trouble f.

This book contains a collection of 11 research and review papers devoted to the topic of fluid-structure interaction. The subject matter is divided into chapters covering a wide spectrum of recognized areas of research, such as: wall bounded turbulence; quasi 2-D turbulence; canopy turbulence; large eddy simulation; lake hydrodynamics; hydraulic hysteresis; liquid impacts; flow induced.

In this paper the issue of the coherent structures of turbulence developing in wall-bounded flows is addressed. After a short historical synthesis, some basic concepts are reviewed and the idea of coherent structure is by: Advances in Turbulence VI presents an update on the state of turbulence research with some bias towards research in Europe, since it represents an almost complete collection of the paper presentations at the Sixth European Turbulence Conference, sponsored by EUROMECH, ERCOFTAC and COST, and held at the Swiss Federal Institute of Technology in Lausanne, July TURBULENT CHANNEL FLOW AT LOW REYNOLDS NUMBERS Master of Applied Science, Evolution of three ejections Counter-rotating spanwise vortices fiom shear layer.

Figure Formation of hairpin vortex Author: Peter Mang-Yu Chung. Topics: Engineering simulation, Scalars, Simulation, Vortices, Flow (Dynamics), Channel flow, Diffusion (Physics), Reynolds number, Vorticity Evaluation of Performance and Code-to-Code Variation of a Dynamic Hybrid RANS/LES Model for Simulation of Backward-Facing Step Flow.

Then, nonlinear evolution of large-scale vortices and Kelvin-Helmholtz waves in relaxing shear flows are studied. Critical Reynolds numbers in supersonic Couette flows are calculated analytically and numerically within the framework of both linear and nonlinear classical energy .Evolution of the flow visualizations (right) ranging from the initial at t*=0, to transition (t*~9) to increasingly organized smaller-scale vortices (top row), and then to fully developed (disorganized) worm-vortex flow characteristic of turbulence (t*>30).Full text of "Flow control [electronic resource]: fundamentals and practices" See other formats.