ON SUBLAYER ERUPTION AND VORTEX FORMATION

Theory and computations are discussed regarding the sublayer eruption and subsequent formation of a strong vortex locally, in the near-wall dynamics of transitional-turbulent boundary layers or during dynamic stall. Finite-time break-up of unsteady interacting boundary layers is addressed first, with comparisons between nonlinear theory and computations. Second, the next two stages are described, where normal pressure gradients and a nonlinear critical-layer jump come into operation, followed by a strong vortex wind-up. Further discussion including the three-dimensional setting and the computational implications is also presented.