Instability of Lenticular Vortices: Results from Laboratory Experiments, Linear Stability Analysis and Numerical Simulations

Noé Lahaye (1, 2) , Alexandre Paci (3) , Stefan Llewellyn Smith (4)

1 IRMAR - Institut de Recherche Mathématique de Rennes
2 FLUMINANCE - Fluid Flow Analysis, Description and Control from Image Sequences
3 CNRM - Centre national de recherches météorologiques
4 MAE - UC San Diego - Department of Mechanical and Aerospace Engineering [Univ California San Diego]

The instability of surface lenticular vortices is investigated using a comprehensive suite of laboratory experiments combined with numerical linear stability analysis as well as nonlinear numerical simulations in a two-layer Rotating Shallow Water model. The development of instabilities is discussed and compared between the different methods. The linear stability analysis allows for a clear description of the origin of the instability observed in both the laboratory experiments and numerical simulations. While global qualitative agreement is found, some discrepancies are observed and discussed. Our study highlights that the sensitivity of the instability outcome is related to the initial condition and the lower-layer flow. The inhibition or even suppression of some unstable modes may be explained in terms of the lower-layer potential vorticity profile.

Domaines: Mécanique des fluides [physics.class-ph]; Planète et Univers [physics]

Noé Lahaye, Alexandre Paci, Stefan Llewellyn Smith. Instability of Lenticular Vortices: Results from Laboratory Experiments, Linear Stability Analysis and Numerical Simulations. Fluids, 2021, 6 (11), pp.1-25. ⟨10.3390/fluids6110380⟩. ⟨hal-03423747⟩