Isotropization at small scales of rotating helically driven turbulence

We present numerical evidence of how three-dimensionalization occurs at small scale in rotating turbulence with Beltrami ($\mathit{ABC}$) forcing, creating helical flow. The Zeman scale ${\ell }_{\Omega } $ at which the inertial and eddy turn-over times are equal is more than one order of magnitude...

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Bibliographic Details
Published in:Journal of fluid mechanics 2012-05, Vol.699, p.263-279
Main Authors: Mininni, P. D., Rosenberg, D., Pouquet, A.
Format: Article
Language:English
Subjects:
Computational fluid dynamics
Dissipation
Exact sciences and technology
Fluid dynamics
Fluid flow
Fundamental areas of phenomenology (including applications)
Helicity
Inertial
Isotropic turbulence
homogeneous turbulence
Physics
Spectra
Turbulence
Turbulent flow
Turbulent flows, convection, and heat transfer
Wave power
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Summary:We present numerical evidence of how three-dimensionalization occurs at small scale in rotating turbulence with Beltrami ($\mathit{ABC}$) forcing, creating helical flow. The Zeman scale ${\ell }_{\Omega } $ 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 $E$ and helicity $H$, and dissipation) each moderately resolved. These results stem from the analysis of a large direct numerical simulation on a grid of $307{2}^{3} $ points, with Rossby and Reynolds numbers, respectively, equal to $0. 07$ and $2. 7\ensuremath{\times} 1{0}^{4} $. At scales smaller than the forcing, a helical wave-modulated inertial law for the energy and helicity spectra is followed beyond ${\ell }_{\Omega } $ by Kolmogorov spectra for $E$ and $H$. Looking at the two-dimensional slow manifold, we also show that the helicity spectrum breaks down at ${\ell }_{\Omega } $, a clear sign of recovery of three-dimensionality in the small scales.
ISSN:0022-1120
1469-7645
DOI:10.1017/jfm.2012.99