A Predictive Framework for Flow Reversals and Excursions in Turbulence

We present a dynamical framework for intermittent reversals and excursions (R&Es) of large-scale circulations in turbulence.

We show that R&Es can arise when turbulent trajectories in phase space shadow invariant manifolds of certain unstable periodic orbits (UPOs).

Consequently, substantial flow reorganization and extreme fluctuations in flow metrics observed during R&Es can be reconstructed by splicing unstable manifolds of such dynamically relevant UPOs.

Using this geometrical framework, we predict imminent R&Es and preemptively avert these extreme events using closed-loop control.