Flow separation from curved surfaces occurs in numerous highly-load engineering components: wings, turbomachine blades, intake ducts, cylinders and diffusers, to name but a few examples. The ability to predict separation is an important engineering requirement, because of the substantial effect separation has on drag, lift, moments, losses, vibrations and noise. However, this is an especially challenging task, because the separation location is not fixed by the geometry, varies greatly in time and space and is highly sensitive to the turbulence dynamics near the wall from which the flow separates. The lecture will identify these challenges and provide a summary of the current predictive capabilities of modelling and simulation strategies for separated flows, with an emphasis on aerodynamic configurations.