Cascades in helical turbulence.
We suggest the existence of a characteristic inner scale xi for helicity dissipation in a regime of hydrodynamic fully developed turbulence and estimate it on dimensional grounds. This scale is always larger than the Kolmogorov scale eta and their ratio eta/xi vanishes in the high Reynolds number limit, so the flow will always be helicity free in the small scales. These ideas are illustrated in a shell model of turbulence.
Ditlevsen
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The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen O, Denmark.
Giuliani
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