Ducimetière, Yves-MarieBoujo, EdouardGallaire, François2024-05-072024-05-072024-05-07202410.1103/PhysRevFluids.9.053905https://infoscience.epfl.ch/handle/20.500.14299/207838We consider fluid flows, governed by the Navier-Stokes equations, subject to a steady symmetry-breaking bifurcation and forced by a weak noise acting on a slow timescale. By generalizing the multiple-scale weakly nonlinear expansion technique employed in the literature for the response of the Duffing oscillator, we rigorously derive a stochastically forced Stuart-Landau equation for the dominant symmetry-breaking mode. The probability density function of the solution, and of the escape time from one attractor to the other, are then determined by solving the associated Fokker-Planck equation. The validity of this reduced order model is tested on the flow past a sudden expansion for a given Reynolds number and different noise amplitudes. At a very low numerical cost, the statistics obtained from the amplitude equation accurately reproduce those of long-time direct numerical simulations.BifurcationsLow-dimensional modelsNonlinear dynamics in fluidsNoise-induced transitions past the onset of a steady symmetry-breaking bifurcation: The case of the sudden expansiontext::journal::journal article::research article