LOCAL ENERGY FLUX AND SUBGRID-SCALE STATISTICS IN 3-DIMENSIONAL TURBULENCE

Statistical properties of the subgrid-scale stress tensor, the local e nergy flux and filtered velocity gradients are analysed in numerical s imulations of forced three-dimensional homogeneous turbulence. High Re ynolds numbers are achieved by using hyperviscous dissipation. It is f ound that in the inertial range the subgrid-scale stress tensor and th e local energy flux allow simple parametrization based on a tensor edd y viscosity. This parametrization underlines the role that negative sk ewness of filtered velocity gradients plays in the local energy transf er. It is found that the local energy flux only weakly correlates with the locally averaged energy dissipation rate. This fact reflects basi c difficulties of large-eddy simulations of turbulence, namely the pos sibility of predicting the locally averaged energy dissipation rate th rough inertial-range quantities such as the local energy flux is limit ed. Statistical properties of subgrid-scale velocity gradients are sys tematically studied in an attempt to reveal the mechanism of local ene rgy transfer.