MASS Seminar - David Nolan (Miami)
Date Time Location
November 15th, 2013 11:00am-12:00pm
Title: "Dynamics of the Tornado Vortex"

In the first part of this talk, I will review the basic mechanisms for
all tornado-like vortices (tornadoes, waterspouts, and dust devils). Our
current understanding of what controls their intensity, structure, and
dynamics comes from both laboratory experiments and numerical simulations.
In particular, the "thermodynamic speed limit" sets a fairly low upper
limit on the maximum mean wind speeds compared to the levels of damage
that are found in the most extreme events.

The most extreme wind speeds are associated with asymmetric, coherent
structures such as "multiple vortices" that are often visible in
photographs and videos. A new analysis of the multiple vortex phenomenon
will be presented using much more realistic representations of the
tornado-vortex flow than had been used in some earlier studies. The
linearized stability analysis successfully predicts the dominant
structures in unsteady, three-dimensional simulations. In addition,
symmetric modes are identified that may explain symmetric oscillations
that have been directly observed in real tornadoes.


Speaker's website: http://www.rsmas.miami.edu/personal/dnolan/