Universality of anisotropic fluctuations from numerical simulations of turbulent flows

We present new results from a direct numerical simulation of a three-dimensional homogeneous Rayleigh-Bénard system (HRB), i.e. a convective cell with an imposed linear mean temperature profile along the vertical direction. We measure the SO (3)-decomposition of both velocity structure functions and buoyancy terms. We give a dimensional prediction for the values of the anisotropic scaling exponents in this Rayleigh-Bénard systems. Measured scaling does not follow dimensional estimate, while a better agreement can be found with the anisotropic scaling of a different system, the random -Kolmogorov-flow (RKF) (Biferale L., Daumont I., Lanotte A. and Toschi F. Phys. Rev. E , 66 (2002) 056306). Our findings support the conclusion that scaling properties of anisotropic fluctuations are universal , i.e. independent of the forcing mechanism sustaining the turbulent flow.