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Accueil > Actualités > Séminaires > Séminaires 2013

Mardi 16 avril 2013, 11h00 LEGI salle A103

Peter J. Diamessis, Associate Professor, School of Civil and Environmental Engineering and Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853, U.S.A.

Titre/Title :
The internal wave field radiated by a stratified turbulent wake

Contact :
Chantal Staquet (MEIGE)

Résumé/Abstract :
This talk will present results from numerical simulations of a stratified turbulent wake with non-zero net momentum over a broad range of body-based Reynolds number and Froude numbers. The focus will be on the wake-radiated internal gravity wave (IGW) field. At the higher Reynolds numbers values considered, which are one order of magnitude higher than those attained in the laboratory, secondary Kelvin-Helmholtz instabilities and turbulence in the wake core drive persistent IGW radiation up to much later times than commonly expected. Through two-dimensional wavelet analysis, the wavelengths, group/phase velocities and orientation angle of the wake-emitted IGW field are estimated. At the higher Reynolds number value, IGW beams/packets propagate at an angle closer to the horizontal plane suggesting that the wave-generation mechanism is no longer viscously controlled but serves to efficiently extract momentum from the mean wake flow. Finally, the steepness of the near-field waves increases with Reynolds and Froude number, indicating potential for enhanced remote wave breaking in geophysical/naval environments.