Intermittency of coherent structures - An approach using statistical theories of isotropic turbulence

Some mechanisms based on statistical theories of turbulence are proposed which make it possible to gain a better understanding of the intermittent behavior of coherent structures in turbulent flows. It is shown that the dynamics of these flows is characterized by a competition between the organizing action of external forces of instability mechanisms tending to create coherent structures and the exposive growth of small-scale three-dimensionality tending to destroy them. Thus, the coherent structures are intermittently destroyed by three-dimensional turbulence and then reformed due to instability. The theory, although developed for the turbulent free shear layer, can be extended to rotating turbulence.