Random changes of flow topology in two dimensional and geophysical turbulence

Freddy Bouchet (1) , Eric Simonnet (1)

1 INLN - Institut Non Linéaire de Nice Sophia-Antipolis

We study the two dimensional (2D) stochastic Navier Stokes (SNS) equations in the inertial limit of weak forcing and dissipation. The stationary measure is concentrated close to steady solutions of the 2D Euler equation. For such inertial flows, we prove that bifurcations in the flow topology occur either by changing the domain shape, the nonlinearity of the vorticity-stream function relation, or the energy. Associated to this, we observe in SNS bistable behavior with random changes from dipoles to unidirectional flows. The theoretical explanation being very general, we infer the existence of similar phenomena in experiments and in models of geophysical flows.

Mots clés: Large scales of turbulent flows; twodimensional turbulence; geophysical turbulence; out of equilibrium statistical mechanics; bistability

Domaines: Dynamique Chaotique [nlin.CD]; Mécanique statistique [cond-mat.stat-mech]; Mécanique des fluides [physics.class-ph]

Freddy Bouchet, Eric Simonnet. Random changes of flow topology in two dimensional and geophysical turbulence. 2008. ⟨hal-00273264⟩