SLS Seminar: Jay Brett (MIT)
Competition between Chaotic Advection and Diffusion: Stirring and Mixing in a 3D Eddy Model
In submesoscale ocean features, both vertical motions and diffusion can be non-negligible factors. Vertical motions allow for chaotic advection to be present even in steady flows, as has been shown for an Ekman-driven rotating cylinder analogue of a submesoscale eddy. The current work considers the importance of diffusion as compared to chaotic advection for tracers in this rotating cylinder. Three methods are used to quantify the relative importance: scaling arguments; the spread of ensembles of trajectories; and numerical simulations of dye release. Through these complementary methods, I show that chaotic advection will dominate turbulent diffusion in the widest chaotic regions. In thin chaotic regions, diffusion is at least as important as chaotic advection. This scale separation indicates a lower limit to when Lagrangian coherent structures are useful.
About the Series
The Atmosphere, Ocean and Climate Sack Lunch Seminar Series is an informal seminar series within PAOC that focuses on more specialized topics than the PAOC Colloquium. Seminar topics include all research concerning the science of atmosphere, ocean and climate. The seminars usually take place on Wednesdays from 12-1pm in 54-915. The presentations are either given by an invited speaker or by a member of PAOC and can focus on new research or discussion of a paper of particular interest.