European Turbulence Conference 14

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Vorticity Statistics and the Time Scales of Turbulent Strain

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Time scales of turbulent strain activity, denoted as the strain persistence times of first and second order, are obtained from time-dependent expectation values and correlation functions of lagrangian rate-of-strain eigenvalues taken in particularly defined statistical ensembles. Our approach is based on a gaussian closure approximation for single-point vorticity statistics, devised to yield a simple and computationally efficient method for the evaluation of the strain persistence times. We find that softly divergent prefactors correct the usual “1/s” time-scale estimate of standard turbulence phenomenology, a fact that turns out to be of fundamental importance in the emergence of turbulent intermittency. The theoretical framework is supported by a straightforward analysis of direct numerical simulation data.


Luca Moriconi    
Instituto de Física - Universidade Federal do Rio de Janeiro

Rodrigo Pereira    
Divisão de Metrologia em Dinâmica de Fluidos - Instituto Nacional de Metrologia, Normalização e Qualidade Industrial


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