Anisotropic energy transfers in rotating turbulence

Abstract

We investigate experimentally the anisotropic energy transfers in freely decaying turbulence subjected to a background rotation. The energy distribution E(r,t) = 〈(δu)2〉 and the anisotropic energy flux density F(r) = 〈δu(δu)2〉, where δu is the vector velocity increment over separation r, are determined from large data sets of Particle Image Velocimetry measurements. Surprisingly, although E(r) is strongly anisotropic at all scales, F(r) remains almost radial, except in the near-dissipative range. The anisotropy growth of decaying rotating turbulence is therefore proved to be essentially driven by a nearly radial, but orientation-dependent, energy flux density F(r).