Small-scale intermittency in anisotropic turbulence.

Isotropic, rotating, and stratified turbulent flows are analyzed using a scale- and direction-dependent flatness. The anisotropy of the spatial fluctuations of the energy distribution can hereby be quantified for different length scales. This measure allows one to distinguish between longitudinal and transversal intermittency as well as between horizontal and vertical intermittency. The difference between longitudinal and transversal intermittency is argued to be related to the incompressiblity constraint. A large difference between horizontal and vertical intermittency for stratified turbulence can be explained by an energy depletion of the horizontal plane in Fourier space.