Eulerian vs Lagrangian Irreversibility in an experimental turbulent swirling flow

Adam Cheminet (1, 2) , Damien Geneste (1, 2) , Antoine Barlet (1, 2) , Yasar Ostovan (3) , Tarek Chaabo (3) , Valentina Valori (1, 2) , Paul Debue (1, 2) , Christophe Cuvier (3) , François Daviaud (1, 2) , Jean-Marc Foucaut (3) , Jean-Philippe Laval (3) , Vincent Padilla (1, 2) , Cécile Wiertel (1, 2) , Bérengère Dubrulle (1, 2)

1 SPEC - UMR3680 - Service de physique de l'état condensé
2 SPHYNX - Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes
3 LMFL - Laboratoire de Mécanique des Fluides de Lille - Kampé de Fériet

In a turbulent fluid, the time-reversal symmetry is explicitly broken by viscosity, and spontaneously broken in the inviscid limit. Recently, Drivas proved the equivalence of two different local indicators of time-irreversibility: i) an Eulerian one, based on regularity properties of the velocity field ii) a Lagrangian one, based on symmetry properties of the trajectories under time reversal. We test this equivalence in a turbulent Von Kármán experiment at a resolution of the order of the Kolmogorov scale using a high resolution 4D-PTV technique. We use the equivalence to perform the first joined Eulerian-Lagrangian exploration of the dynamics leading to time irreversibility, and find that it is linked with vortex interaction, suggesting a link between irreversibility and singularity.

Domaines: Physique [physics]; Mécanique des fluides [physics.class-ph]

Adam Cheminet, Damien Geneste, Antoine Barlet, Yasar Ostovan, Tarek Chaabo, et al.. Eulerian vs Lagrangian Irreversibility in an experimental turbulent swirling flow. Physical Review Letters, 2022, 129 (12), pp.124501. ⟨10.1103/PhysRevLett.129.124501⟩. ⟨hal-03765230⟩