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| Yim, Eunok; Billant, Paul; Menesguen, Claire. |
| This paper investigates the stability of an axisymmetric pancake vortex with Gaussian angular velocity in radial and vertical directions in a continuously stratified-rotating fluid. The different instabilities are determined as a function of the Rossby number Ro, Froude number Fh, Reynolds number Re and aspect ratio α. Centrifugal instability is not significantly different from the case of a columnar vortex due to its short-wavelength nature: it is dominant when the absolute Rossby number |Ro| is large and is stabilized for small and moderate |Ro| when the generalized Rayleigh discriminant is positive everywhere. The Gent–McWilliams instability, also known as internal instability, is then dominant for the azimuthal wavenumber m=1 when the Burger number... |
| Tipo: Text |
Palavras-chave: Geophysical and geological flows; Vortex flows; Vortex instability. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00347/45817/46635.pdf |
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| Reinaud, Jean N.; Carton, Xavier. |
| We examine the interactions between two three-dimensional quasi-geostrophic hetons. The hetons are initially translating towards one another. We address the effect of the vertical distance between the two poles (vortices) constituting each heton on the interaction. We also examine the influence of the horizontal separation between the poles within each heton. In this investigation, the two hetons are facing each other. Two configurations are possible depending on the respective locations of the like-signed poles of the hetons. When they lie at the same depth, we refer to the configuration as symmetric; the antisymmetric configuration corresponds to opposite-signed poles at the same depth. The first step in the investigation uses point vortices to represent... |
| Tipo: Text |
Palavras-chave: Geophysical and geological flows; Quasi-geostrophic flows; Vortex dynamics. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00277/38796/37470.pdf |
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| Reinaud, Jean N.; Carton, Xavier. |
| We investigate numerically the nonlinear interactions between hetons. Hetons are baroclinic structures consisting of two vortices of opposite sign lying at different depths. Hetons are long-lived. They most often translate (they can sometimes rotate) and therefore they can noticeably contribute to the transport of scalar properties in the oceans. Heton interactions can interrupt this translation and thus this transport, by inducing a reconfiguration of interacting hetons into more complex baroclinic multipoles. More specifically, we study here the general case of two hetons, which collide with an offset between their translation axes. For this purpose, we use the point vortex theory, the ellipsoidal vortex model and direct simulations in the... |
| Tipo: Text |
Palavras-chave: Baroclinic flows; Geophysical and geological flows; Quasi-geostrophic flows. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00333/44401/44157.pdf |
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| Ardhuin, Fabrice; Herbers, T. H. C.. |
| Oceanic pressure measurements, even in very deep water, and atmospheric pressure or seismic records, from anywhere on Earth, contain noise with dominant periods between 3 and 10 s, which is believed to be excited by ocean surface gravity waves. Most of this noise is explained by a nonlinear wave-wave interaction mechanism, and takes the form of surface gravity waves, acoustic or seismic waves. Previous theoretical work on seismic noise focused on surface (Rayleigh) waves, and did not consider finite-depth effects on the generating wave kinematics. These finite-depth effects are introduced here, which requires the consideration of the direct wave-induced pressure at the ocean bottom, a contribution previously overlooked in the context of seismic noise. That... |
| Tipo: Text |
Palavras-chave: Acoustics; Geophysical and geological flows; Surface gravity waves. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00125/23580/21479.pdf |
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