Lagrangian statistics for Navier-Stokes turbulence under Fourier-mode reduction: fractal and homogeneous decimations

Lagrangian statistics for Navier-Stokes turbulence under Fourier-mode reduction : fractal and homogeneous decimations

QC 20170116
We study small-scale and high-frequency turbulent fluctuations in three-dimensional flows under Fourier-mode reduction. The Navier-Stokes equations are evolved on a restricted set of modes, obtained as a projection on a fractal or homogeneous Fourier set. We find a strong sensitivity (reduction) of the high-frequency variability of the Lagrangian velocity fluctuations on the degree of mode decimation, similarly to what is already reported for Eulerian statistics. This is quantified by a tendency towards a quasi-Gaussian statistics, i.e., to a reduction of intermittency, at all scales and frequencies. This can be attributed to a strong depletion of vortex filaments and of the vortex stretching mechanism. Nevertheless, we found that Eulerian and Lagrangian ensembles are still connected by a dimensional bridge-relation which is independent of the degree of Fourier-mode decimation.

Bhatnagar, AkshayStockholms universitet,KTH,Nordic Institute for Theoretical Physics NORDITA,Nordiska institutet för teoretisk fysik (Nordita),Stockholm Univ, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden(Swepub:su)akbha (author)
Biferale, Luca (author)
Lanotte, Alessandra S. (author)
Ray, Samriddhi Sankar (author)
KTHNordic Institute for Theoretical Physics NORDITA (creator_code:org_t)

By the author/editor: Buzzicotti, Mich ...; Bhatnagar, Aksha ...; Biferale, Luca; Lanotte, Alessan ...; Ray, Samriddhi S ...

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