Berkeley Fluids Seminar
University of California, Berkeley
Bring your lunch and enjoy learning about fluids!
March 12, 2014
Dr. Eric Arobone (Stanford University)
How Symmetric is Symmetric Instability?
The pure symmetric instability is an instability of oceanic and atmospheric fronts that is independent of the along-front coordinate. Observational evidence suggests that along-front variability in vertical velocity and sea surface temperature anomaly is not negligible. We examine the three-dimensional evolution of frontal shear instabilities from both linear and non-linear perspectives. Linear stability analysis indicates that dominant growth rates are possible when modes are off-symmetric. Additionally, along-front variability results in misalignment of perturbations with respect to isopycnals, yielding strong fluxes across isopycnals. A suite of three-dimensional direct numerical simulations are performed exploring a horizontally homogeneous front with differing horizontal domain sizes. For sufficiently large domains, the front maintains along-front variation and a pure symmetric instability is not observed. Lastly, transition to turbulence is explored using large-scale simulations. Vorticity dynamics and bulk energetics illustrate important features of the transition.