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Turbulence on a fractal is normal!

02/02/2016

The structure of vortex filaments for a turbulent flow living on a fractal set (of dimension D< 3).

The structure of vortex filaments for a turbulent flow living on a fractal set (of dimension D< 3).

An international team of researchers including Dr Alessandra S. Lanotte, Institute of Atmospheric Sciences and Climate, Professors Roberto Benzi and Luca Biferale, from University of  Rome Tor Vergata, together with Professor Federico from Technical University of Eindhoven and Dr. Shiva K. Malapaka from IIIT Bangalore, have found that turbulent flows might eventually loose their wild and intermittent character, if they are confined on a fractal. The results were published on 31 December, 2015 on Physical Review Letters (http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.115.264502)

Turbulence is everywhere, in many facets of our daily lives, and it is very easily recognizable by any of us, yet we are not able to analyze it mathematically in a full satisfactory way.          Turbulent flows are weird, loosely predictable, irregulars or, in more quantitative words, they are intermittent. This means that in turbulent flows extremely large velocity fluctuations are much more probable to happen than in regular flow conditions (when a bell-curve distribution, also called normal distribution, is observed for the velocity fluctuations). Such wild turbulent fluctuations are difficult to control in applications, and we do not understand how they are connected to the dynamics of the flow. 

By means of a novel numerical approach, the Italian, Dutch and Indian team has shown for the first time that it is possible to tame turbulence intermittency, if  the flow is confined to evolve on a fractal set of degrees of freedom. Extreme fluctuations disappear, and turbulence becomes normally distributed. Promising implications for the origin of strong turbulent fluctuations, as well as for numerical modeling applications are envisaged.

Per informazioni:
Alessandra Sabina Lanotte
CNR - Istituto di scienze dell'atmosfera e del clima
CNR ISAC, Str. Prov. Lecce Monteroni, 73100 Lecce
a.lanotte@isac.cnr.it
0832 298814

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