On the Rapid Increase of Intermittency in the Near-Dissipation Range of Fully Developed Turbulence

Intermittency, measured as $\log ({F(r)}/{3})$ where $F(r)$ is the flatness of velocity increments at scale r, is found to rapidly increase as viscous effects intensify and eventually saturate at very small scales. This feature defines an intermediate range of scales between the inertial and dissipation ranges, that we shall call near-dissipation range. It is argued that intermittency is multiplied by a universal factor throughout the near-dissipation range, while the (logarithmic) extension of the near-dissipation range varies as $\sqrt{\log Re}$ with the Reynolds number. As a consequence, scaling properties of velocity increments in the near-dissipation range strongly depend on Re.