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Article Dans Une Revue Physical Review Fluids Année : 2023

Observation of inertia-gravity wave attractors in an axisymmetric enclosed basin

Observation d'attracteurs d'onde d'inertie-gravité dans un bassin axi-symétrique

Corentin Pacary
Thierry Dauxois
Evgeny Ermanyuk
Pascal Metz
Marc Moulin
Sylvain Joubaud

Résumé

Internal waves are ubiquitous in the ocean and play an essential role in the transport of energy and mixing. Their peculiar reflection enables the concentration of energy on a limit cycle. With wave beams viewed as rays, this reflection on an inclined slope shrinks its width and generically brings closer two initially different trajectories eventually reaching a limit cycle called an attractor. Following previous studies, a ray-tracing algorithm is used to track the convergence of wave beams onto such a structure in a 3D axisymmetric domain. This information is used to design experiments using a truncated conical shaped tank in order to form an inertia-gravity waves attractor in a 3D axisymmetric geometry. By increasing the amplitude of the forcing, an evolution of the attractor characteristics can be observed. The occurrence of waves at frequencies lower than the forcing frequency ω 0 suggests triadic resonant instability in a rotating or in a stratified case. Experiments performed in a stratification-only or a rotation-only case indicate two distinct behaviors. The existence of easily excited standing waves, resonant modes of the tank, at frequencies lower than the forcing one enables sharp triadic resonance instability for internal gravity waves, which is not possible for inertial waves. The effect of the symmetry axis is also investigated by adding a cylinder of sufficient diameter at the center of the domain for the wave to reflect on and thereby avoid the interaction on the singularity. Without it, the large amplitude of the waves on the axis triggers nonlinear effects and mixing, denying the access to the wave turbulence regime.
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Dates et versions

hal-04270711 , version 1 (05-11-2023)

Identifiants

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Corentin Pacary, Thierry Dauxois, Evgeny Ermanyuk, Pascal Metz, Marc Moulin, et al.. Observation of inertia-gravity wave attractors in an axisymmetric enclosed basin. Physical Review Fluids, 2023, 8 (10), pp.104802. ⟨10.1103/PhysRevFluids.8.104802⟩. ⟨hal-04270711⟩
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