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.