Extreme events and intermittency in turbulence

P.D. MININNI

Buenos Aires

Congreso; EECOS 2015, ?Extreme events in complex optical systems?; 2015

OSA

The definition of what an extreme event is can be different depending on the physical problem considered. In fluid dynamics, the phenomenon of intermittency is the sine qua non of turbulence, and calls for a precise definition of extreme events and for the development of specific theoretical tools to study them. Indeed, the complexity of a turbulent flow is often associated with the fact that turbulence comes in intermittent ?gusts?. These intermittent gusts (or extreme events) are associated with non-Gaussian statistics of some physical variable of the system. As such, intermittency is a highly spatially and temporally localized phenomenon, which thus requires high-resolution instrumentation, be it in the laboratory, in atmospheric observations, or in numerical simulations. In this talk I will present an introduction to tools from statistics and from dynamical systems that are regularly used to study intermittency and extreme events, including probability density functions of field increments, structure functions, scaling exponents, and modelling using low dynamical systems close to criticality.