The structures responsible for the inverse energy and the forward enstrophy cascades in two-dimensional turbulence

Two-dimensional turbulence admits two different ranges: an inverse energy cascade at large scales and a cascade of enstrophy to the small scales. Here we show that two flow structures govern the transfers of either enstrophy or energy. Vortical structures are responsible for the transfers of energy upscale while filamentary structures are responsible for the forward transfer of the enstrophy