An analysis of the energy transfer and the locality of nonlinear interactions in turbulence

Using the results of direct numerical simulations of isotropic turbulence, we compute detailed energy exchanges between different scales of motion and investigate how they contribute to the global quantities such as the energy transfer, the spectral energy flux, and the subgrid-scale dissipation. The scales of motion are defined by decomposing velocity fields using sharp spectral and smooth, tangent hyperbolic filters. The analysis of detailed interactions reveals that individual nonlocal contributions are large but significant cancellations lead to the global quantities asymptotically dominated by the local interactions. Implications of these results for turbulence modeling are discussed. (C) 2007 American Institute of Physics.