This review summarizes fundamental results and discoveries concerning vortex-induced vibration (VIV), that have been made over the last two decades, many of which are related to the push to explore very low mass and damping, and to new computational and experimental techniques that were hitherto not available. We bring together new concepts and phenomena generic to VIV systems, and pay special attention to the vortex dynamics and energy transfer that give rise to modes of vibration, the importance of mass and damping, the concept of a critical mass, the relationship between force and vorticity, and the concept of "effective elasticity," among other points. We present new vortex wake modes, generally in the framework of a map of vortex modes compiled from forced vibration studies, some of which cause free vibration. Some discussion focuses on topics of current debate, such as the decomposition of force, the relevance of the paradigm flow of an elastically mounted cylinder to more complex systems, and the relationship between forced and free vibration.

/pdf/vortex-induced-vibrations-5ae1ijrmof.pdf

Vortex-induced vibrations

Dynamics of structures

Méthodes : Sur une série de 31 femmes présentant des varices périnéales d’origine extrasaphéniennes ayant bénéficié d’une exploration radiologique veineuse pelvienne et de l’embolisation des veines incontinentes nous avons étudié les résultats et les corrélations anatomo-clinique entre les varices et les signes cliniques de l’insuffisance veineuse pelvienne. Un sous-groupe B de 23 patientes présentant une insuffisance veineuse pelvienne et des signes cliniques a été comparé à un groupe A de 4 patientes qui ne présentaient pas d’insuffisance veineuse pelvienne à l’exploration. Nous avons choisi d’étudier 3 signes cliniques : la douleur pelvienne et la douleur des membres inférieurs survenant au début ou pendant les règles ainsi que la dyspareunie. La symptomatologie a été évaluée sur une échelle analogique de 0 à 10 et un score clinique (de 0 à 30) a été établi en ajoutant ces 3 chiffres.

http://link.springer.com/content/pdf/10.1007/BF02973687.pdf

Références bibliographiques: La fibroscopie bronchique

https://yakari.polytechnique.fr/Django-pub/documents/matteo2004rp-2pp.pdf

Coupling of Structure and Wake Oscillators in Vortex-Induced Vibrations

An overview of modeling and experiments of vortex-induced vibration of circular cylinders

We investigate the vortex-induced vibrations (VIV) of a very slender cable subjected to a stationary uniform cross-flow, using a travelling wave approach. A phenomenological model of the near wake based on van der Pol oscillators is developed and tested in comparison with numerical simulations and experimental data. A selection criterion for vortex-induced waves (VIW) is established: the fluid selects the frequency, according to Strouhal's law, and the structure fixes the wavenumber, as dictated by its dispersion relation.

Vortex-induced travelling waves along a cable

A modal computation of a complete clarinet is presented by the association of finite-element models of the reed and of part of the pipe with a lumped-element model of the rest of the pipe. In the first part, we compare modal computations of the reed and the air inside the mouthpiece and barrel with measurements performed by holographic interferometry. In the second part, the complete clarinet is modeled by adjoining a series of lumped elements for the remaining part of the pipe. The parameters of the lumped-resonator model are determined from acoustic impedance measurements. Computed eigenmodes of the whole system show that modal patterns of the reed differ significantly whether it is alone or coupled to air. Some modes exhibit mostly reed motion and a small contribution of the acoustic pressure inside the pipe. Resonance frequencies measured on a clarinet with the mouthpiece replaced by the cylinder of equal volume differ significantly from the computed eigenfrequencies of the clarinet taking the actual shape of the mouthpiece into account and from those including the (linear) dynamics of the reed. This suggests revisiting the customary quality index based on the alignment of the peaks of the input acoustical impedance curve.

/pdf/numerical-and-experimental-modal-analysis-of-the-reed-and-4ydt8ztw6w.pdf

Numerical and experimental modal analysis of the reed and pipe of a clarinet.

http://www.off-ladhyx.polytechnique.fr/people/matteo/cras2002.pdf

Matteo Luca Facchinetti

Papers

Coupling of Structure and Wake Oscillators in Vortex-Induced Vibrations

Vortex-induced travelling waves along a cable

Numerical and experimental modal analysis of the reed and pipe of a clarinet.

Vortex shedding modeling using diffusive van der Pol oscillators

Fatigue damage of materials and structures assessed by Wöhler and Gassner frameworks: recent insights about load spectra for the automotive