ELFT HÍRADÓ

[StatFizSzeminar <statfiz AT glu.elte.hu>]

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          We apologize for the series of errors, the date 
       is in fact the 9th. The final correct announcement is      
        
                  
              ELTE Institute of Theoretical Physics
                SEMINARS IN STATISTICAL PHYSICS
                    
                Wednesday, June 9, 2004,  11:00

                    Raymond T. Pierrehumbert          

              University of Chicago and ENS, Paris 


              Global path statistics on random walks
                        with applications 
             to some nonlinear fluid mixing problems


We consider the problem of the evolution of the concentration of an
active scalar subject to fluid advection, diffusion, and nonlinear
source-sink processes. The archetype for this class of problems is that
of the evolution of a condensible substance, such as water vapor. The
water vapor problem itself has profound importance for the physics of
climate change. In the class of problems under discussion, the
probability distribution of the tracer depends on statistics of the past
particle paths that are global, in the sense that they depend on the
entire path history and not just its final positions. Such problems
present novel challenges, not the least of which is the
non-commutativity of mixing and condensation, and also the difficulty of
deriving a bulk transport equation (analogous to the diffusion equation
derived from a microscopic random walk). Simulations and theoretical
results exploring the behavior of nonlinear active scalar mixing systems
will be presented. The exploration of this problem is also used as an
opportunity to illustrate the virtue of using the computer language
Python as a tool to explore the behavior of dynamical systems.


    1117 Bp. Pazmany P. setany 1A, 2nd floor, lecture room 2.54
             www site: http://glu.elte.hu/~statfiz/  
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