[Todos] Coloquios DF: Mark Rast (CU Boulder): Jueves 22/5, 14hs, Aula Seminario, 2do piso, Pab. I

[Augusto Roncaglia]

 COLOQUIOS DEL DEPARTAMENTO DE F�SICA FCEYN - UBA


              En el Aula Seminario, 2do piso, Pab. I,

              Jueves 22/5, 14hs:

              MARK RAST

              UNIVERSITY OF COLORADO BOULDER.

*              Turbulence: Are transport models possible or necessary? What
might they look like?*

It has been said that turbulence is the last important unsolved problem of
classical physics. But what is the problem? Why is it so difficult to
solve? And why work so hard to solve it? Is it possible that with ever
increasing computational capabilities the problem will be bypassed before
being solved? I will suggest that while advances in computational
capabilities over the next decades may allow fundamental advances,
understanding, not raw computer power, will remain the essential solution
ingredient. Given this motivation, I will discuss recent efforts to employ
mixed Eulerian/Lagrangian statistics to model scalar transport in a simple
analog flow, that of a collection of point vortices. As expected, the mean
squared Eulerian displacement along Lagrangian trajectories in such a flow
scales ballistically for times shorter than the integral time and
diffusively for longer times. However, the displacement distribution at any
given time only approximates that of a random walk. Over inertial time
scales, the probability of long distance transport is reduced from a random
walk, and over times shorter than the Kolmogorov or longer than the
integral times, the probability of long distance transport is enhanced.
These deviations are due to the spatial and temporal intermittency of the
flow, and can be statistically modeled as a collection of trapping events
with durations uniformly distributed between the Kolmogorov and integral
time scales. The findings have implications for turbulent transport beyond
the simplified flow studied.
------------ próxima parte ------------
Se ha borrado un adjunto en formato HTML...
URL: http://mail.df.uba.ar/pipermail/todos/attachments/20140520/f6583275/attachment.html