title: Inverse energy cascade in nonlocal helical shell models of turbulence.
abstract: Following the exact decomposition in eigenstates of helicity for the Navier-Stokes equations in Fourier space [F. Waleffe, Phys. Fluids A 4, 350 (1992)], we introduce a modified version of helical shell models for turbulence with nonlocal triadic interactions. By using both an analytical argument and numerical simulation, we show that there exists a class of models, with a specific helical structure, that exhibits a statistically stable inverse energy cascade, in close analogy with that predicted for the Navier-Stokes equations restricted to the same helical interactions. We further support the idea that turbulent energy transfer is the result of a strong entanglement among triads possessing different transfer properties.
authors.affiliation: Dip. di Fisica and INFN, Università "Tor Vergata," Via della Ricerca Scientifica 1, I-00133 Roma, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: De Pietro
authors.affiliation: Dip. di Fisica and INFN, Università "Tor Vergata," Via della Ricerca Scientifica 1, I-00133 Roma, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Biferale
authors.affiliation: Instituto Nacional de Matemática Pura e Aplicada-IMPA, Est. Dona Castorina 110, Rio de Janeiro 22460-320 Brazil.
authors.forename: Alexei A
authors.initials: AA
authors.lastname: Mailybaev