Intermittency and coherent structures in two-dimensional turbulence

Abstract

The authors study the mechanisms of enstrophy transfer in 2D turbulence. By theoretical discussion of the fragmentation process at very small scales, the authors show that enstrophy transfer must be space filling, due to the regularity of the flow at any time. Detailed analysis of a numerical decaying experiment confirms this picture. Yet 'intermittency' is acting at large scale due to the presence of coherent structures, namely vortices, which inhibit local enstrophy transfer.