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

TL;DR

This paper investigates how intermittency in turbulence sharply increases and saturates at small scales, revealing a universal factor and a Reynolds number-dependent near-dissipation range with implications for velocity increment scaling.

Contribution

It introduces the concept of a near-dissipation range where intermittency rapidly increases and saturates, highlighting a universal multiplicative factor and Reynolds number dependence.

Findings

Intermittency increases rapidly and saturates at small scales.

The near-dissipation range extends as rac12;log Re.

Velocity increment scaling depends on Reynolds number.

Abstract

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 a finite 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, independent of the Reynolds number Re, throughout the near-dissipation range. The (logarithmic) extension of the near-dissipation range varies as \sqrt(log Re). As a consequence, scaling properties of velocity increments in the near-dissipation range strongly depend on the Reynolds number.