Computational Fluid Dynamics group,

We present LES simulations of the flow over a wing with sinusoidal leading edge undulations. The undulations act as a passive flow control device, offering superior post-stall aerodynamic performance relative to the unmodified wing with the same mean chord. The baseline case of a reg-ular wing is also presented for comparison. In all cases the Reynolds number based on bulk velocity and mean chord is equal to 120,000, and the angle of attack is set to 20◦. The study explores the details of the flow physics and the mechanisms by which the post-stall aerodynamic bene-fit is gained. For the particular set of geometrical and aero-dynamic parameters considered, a hitherto unreported phys-ical mechanism by which the undulation offers their bene-fit is observed. This increased understanding of the flow physics for the current configuration is an important step towards a more general understanding and the incorpora-tion of the technology into practical designs. Potential ap-plications include vertical axis wind turbines, unmanned air vehicles, helicopter blades, and canard surfaces; the present Reynolds number is of particular relevance to the first two of these applications