Scale interactions and non-local flux in hydrodynamic turbulence

P.D. MININNI, A. ALEXAKIS, Y A. POUQUET

Nagoya, Japón

Simposio; IUTAM Symposium on computational physics and new perspectives in turbulence; 2006

IUTAM

Direct numerical simulations of hydrodynamical turbulence are performed in the presence of a large-scale forcing up to Taylor-based Reynolds numbers of 800 for a Taylor-Green flow and 1000 for ABC forcing. Statistics on the triadic interactions responsible for the transfer of energy, and on their integrated counterparts are obtained from simulations with  a turbulent steady state integrated for more than ten eddy turn-over times. The maximum resolution of the runs performed on regular grids are 1024^3 points. It is shown that the energy transfer is local but at the highest resolution as much as 20% of it comes from non-local interactions involving widely separated scales, with a particular emphasis on the forcing scale. The scaling of the ratio of nonlocal to local energy flux with Reynolds number is found to be a power law.