Skip to Main content Skip to Navigation
Theses

Interaction son-vorticité et retournement temporel, des outils pour la caractérisation acoustique d'écoulements tourbillonnaires

Abstract : Sound-flow interaction constitutes a non-invasive measurement tool in hydro-dynamics. For instance, an acoustic wave crossing a vortex undergoes advection, refraction, and sometimes scattering. The analysis of the wavefront distortion yields the main characteristics of the vortex (position, size, and circulation). In the first part of this work, we show how time-reversal allows to artificially amplify the effect of a vortex on an ultrasonic wave. The use of two transducer arrays leads to a measurement which is both spatial and dynamic. This transmission technique is tested on three model experiments in water. We first locate and quantify the origins of noise and uncertainties. We then validate our technique by studying the precession motion and instabilities of a stretched vortex. Finally, in the case of a vorticity filament, we clearly unveil the presence of sound scattering. The second part is devoted to numerical simulations of our experiments. Three radically different methods are investigated: acoutic ray tracing, a parabolic equation and a finite-difference scheme. We numerically explore the validity of various classical approximations for sound propagation in moving media as well as the effects of the finite aperture of the incident wave. Moreover, taking scattering into account leads to a very good modelling of the experimental data and to an estimation of the vortex size. We eventually propose a numerical study of the field scattered from a vortex core. To conclude, we present a new 2D imaging technique for fluid flows: the acoustic speckle intercorrelation. This ultra-fast technique relies on the analysis of backscattering from suspended particles in the flow. Our first results are promising and add to the transmission technique.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-00002952
Contributor : Sébastien Manneville <>
Submitted on : Wednesday, June 4, 2003 - 5:54:07 PM
Last modification on : Monday, September 28, 2020 - 3:17:23 AM
Long-term archiving on: : Friday, April 2, 2010 - 6:51:47 PM

Identifiers

  • HAL Id : tel-00002952, version 1

Citation

Sébastien Manneville. Interaction son-vorticité et retournement temporel, des outils pour la caractérisation acoustique d'écoulements tourbillonnaires. Dynamique des Fluides [physics.flu-dyn]. Université Paris-Diderot - Paris VII, 2000. Français. ⟨tel-00002952⟩

Share