paper

Isotropisation at small scales of rotating helically-driven turbulence

arXiv:1104.5519 · doi:10.1017/jfm.2012.99

Abstract

We present numerical evidence of how three-dimensionalization occurs at small scale in rotating turbulence with Beltrami (ABC) forcing, creating helical flow. The Zeman scale at which the inertial and eddy turn-over times are equal is more than one order of magnitude larger than the dissipation scale, with the relevant domains (large-scale inverse cascade of energy, dual regime in the direct cascade of energy and helicity , and dissipation) each moderately resolved. These results stem from the analysis of a large direct numerical simulation on a grid of points, with Rossby and Reynolds numbers respectively equal to 0.07 and . At scales smaller than the forcing, a helical wave-modulated inertial law for the energy and helicity spectra is followed beyond by Kolmogorov spectra for and . Looking at the two-dimensional slow manifold, we also show that the helicity spectrum breaks down at , a clear sign of recovery of three-dimensionality in the small scales.

13 pages, 6 figures

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