An analysis of subgrid-resolved scale interactions with use of results from direct numerical simulations

Subgrid nonlinear interaction and energy transfer are analyzed using direct numerical simulations of isotropic turbulence. Influences of cutoff wave n umber at different ranges of scale on the energetics and dynamics have been investigated. It is observed that subgrid-subgrid interaction dominates th e turbulent dynamics when cut-off wave number locates in the energy-contain ing range while resolved-subgrid interaction dominates if it is in the diss ipation range; By decomposing the subgrid energy transfer and nonlinear int eraction into 'forward' and 'backward' groups according to the sign of tria dic interaction, we find that individually each group has very large contri bution, but the net of them is much smaller, implying that tremendous cance llation happens between these two groups.