On the decrease of intermittency in decaying rotating turbulence

Abstract

The scaling of the longitudinal velocity structure functions, $S_q(r)=<|\delta u(r){|}^q>\sim r^{{\zeta }_q}$, is analyzed up to order $q=8$ in a decaying rotating turbulence experiment from a large Particle Image Velocimetry (PIV) dataset. The exponent of the second-order structure function, ${\zeta }_2$, increases throughout the self-similar decay regime, up to the Ekman time scale. The normalized higher-order exponents, ${\zeta }_q/{\zeta }_2$, are close to those of the intermittent non-rotating case at small times, but show a marked departure at larger times, on a time scale ${\Omega }^{-1}$ ($\Omega$ is the rotation rate), although a strictly non-intermittent linear law ${\zeta }_q/{\zeta }_2=q/2$ is not reached.

5 pages, 5 figures. In revision for Phys. Fluids Letters