Eur. Phys. J. E (2018) 41: 48
https://doi.org/10.1140/epje/i2018-11655-2

Regular Article

Time irreversibility in reversible shell models of turbulence

¹ Dipartimento di Fisica, Università di Roma Tor Vergata, Via Ricerca Scientifica 1, 00133, Roma, Italy
² Dipartimento di Fisica and INFN, Università di Torino, via P. Giuria 1, 10125, Torino, Italy
³ Istituto dei Sistemi Complessi, CNR, via dei Taurini 19, 00185, Rome, Italy
⁴ INFN, Sezione di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133, Roma, Italy

^* e-mail: massimo.cencini@cnr.it

Received: 9 October 2017
Accepted: 20 March 2018
Published online: 6 April 2018

Abstract

Turbulent flows governed by the Navier-Stokes equations (NSE) generate an out-of-equilibrium time irreversible energy cascade from large to small scales. In the NSE, the energy transfer is due to the nonlinear terms that are formally symmetric under time reversal. As for the dissipative term: first, it explicitly breaks time reversibility; second, it produces a small-scale sink for the energy transfer that remains effective even in the limit of vanishing viscosity. As a result, it is not clear how to disentangle the time irreversibility originating from the non-equilibrium energy cascade from the explicit time-reversal symmetry breaking due to the viscous term. To this aim, in this paper we investigate the properties of the energy transfer in turbulent shell models by using a reversible viscous mechanism, avoiding any explicit breaking of the symmetry. We probe time irreversibility by studying the statistics of Lagrangian power, which is found to be asymmetric under time reversal also in the time-reversible model. This suggests that the turbulent dynamics converges to a strange attractor where time reversibility is spontaneously broken and whose properties are robust for what concerns purely inertial degrees of freedoms, as verified by the anomalous scaling behavior of the velocity structure functions.