Fluids Seminar “How Symmetric is Symmetric Instability?”

Department of Mechanical Engineering
Fluids Seminar
“How Symmetric is Symmetric Instability?”
Dr. Eric Arobone
Stanford University
Tuesday, March 17, 2015
12:00 p.m.
3110 Etcheverry Hall
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 offsymmetric. 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
Hosted by: Prof. Philip Marcus, 6121 Etcheverry Hall, (510) 642-5942, [email protected]