Bistable flow dynamics of airfoil stall under varying angle of attack: A stochastic model with multiplicative noise

Abstract

We focus on the intermittent bistable stall dynamics of an airfoil under varying angle of attack. We propose a one-dimensional Langevin equation where the stochastic forcing depends on the state of the system -- high-lift attached flow or low-lift detached flow -- and where the deterministic potential depends continuously on the angle of attack. The model, identified based on the flow statistics and dynamics, reproduces the S-shaped lift curve, as well as the flow dynamics. It also predicts the nature of the bifurcations that the flow undergoes as the angle of attack varies.

arXiv commentMain text: 6 pages, 5 figures. Supp. Mat.: 3 pages, 2 figures. Letter accepted in Physical Review E

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