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.