Our velocity measurements on a quasi-two-dimensional turbulent flow in a rapidly rotating annulus yield an inverse cascade with E(k)~k^{ -2} rather than the expected E(k)~k^{ -5/3}. The probability distribution functions for longitudinal velocity differences, \delta_v(r)=v(x+r)-v(x), are self-similar (scale independent) but strongly non-Gaussian, which suggests that the coherent vortices play a significant role. The structure functions, <[\delta_v(r)]^p>~r^{ \zeta_p}, exhibit anomalous scaling: \zeta_p=p/2 rather than \zeta_p=p/3 as in the 1941 Kolmogorov theory.
Categories: physics.flu-dyn