1/k-Spectrum in the Sub-Inertial Domain of Turbulence: A Shell-Model Approach.

English Abstract:

Many physical and astrophysical fluid and plasma turbulent systems display the presence of a 1/f (or 1/k assuming Taylor’s hypothesis) spectral domain at temporal (or spatial) scales above the inertial range, whose origin is still not understood. Here, we investigate the formation of a 1/k spectral domain in fluid and MHD turbulence systems in the sub-inertial range (k < k0 where k0 is the injection scale) by means of shell-model simulations. Our results suggest that the 1/k domain emerges as a consequence of competing direct and inverse cascading process. The relevance of our results for observations in space and astrophysical contexts is briefly discussed.

The research leading to these results has received funding from the European Community’s Seventh Framework Programme ([FP7/2007-2013]) under Grant agreement no. 313038/STORM, MIUR-PRIN grant 2012P2HRCR on “The active Sun and its effects on Space and Earth climate” and the ASI-INAF agreement no. I/022/10/0.