Lagrangian statistics for Navier–Stokes turbulence under Fourier-mode reduction: fractal and homogeneous decimations. (24th November 2016)

• Record Type: Journal Article
• Authors: Buzzicotti, Michele; Bhatnagar, Akshay; Biferale, Luca; Lanotte, Alessandra S; Ray, Samriddhi Sankar
• Is Part Of: New journal of physics. Volume 18:Number 11(2016:Nov.)
• Publication Date: 2016-11-24
• Subjects: isotropic and homogeneous turbulence -- multifractal theory -- Lagrangian dynamics -- intermittency; 47.27.-i -- 82.20.-w -- 47.51.+a -- 47.55.df; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/18/11/113047
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: 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.