INTERMITTENCY AND TURBULENCE

We suggest a mechanism for the appearance of intermittency in fully developed turbulence consistent with the pictures recently presented by Kraichnan [Phys. Rev. Lett. 65, 575 (1990)] and She [Phys. Rev. Lett. 66, 600 (1991)]. The key features in our model are (i) an inverse cascade associated with the spectral density of an additional finite flux motion invariant, leading to (ii) an attempt to form large-scale structures which (iii) are intrinsically unstable to a broadband spectrum of perturbing modes resulting in a secondary transfer of energy to small dissipative scales in intermittent bursts.