Local energy transfer and nonlocal interactions in homogeneous, isotropic turbulence

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Abstract
Detailed computations were made of energy transfer among the scales of motion in incompressible turbulent fields at low Reynolds numbers generated by direct numerical simulations. It was observed that although the transfer resulted from triad interactions that were nonlocal in k space, the energy always transferred locally. The energy transfer calculated from the eddy-damped quasinormal Markovian (EDQNM) theory of turbulence at low Reynolds numbers is in excellent agreement with the results of the numerical simulations. At high Reynolds numbers the EDQNM theory predicts the same transfer mechanism in the inertial range that is observed at low Reynolds numbers, i.e., predominantly local transfer caused by nonlocal triads. The weaker, nonlocal energy transfer is from large to small scales at high Reynolds numbers and from small to large scales at low Reynolds numbers.