Near stall simulation of the flow around an airfoil using zonal RANS/LES coupling method

The objective of this current study is to investigate the course of events leading to stall just before its occurrence. The stall mechanisms are very sensitive to the transition that the boundary layer undergoes near the leading edge of the profile by a Laminar Separation Bubble (LSB). To provide helpful insights into this complex flow, different LES of the flow around an airfoil near stall have been achieved. Attention has been given to the transition mechanism in the LSB. In particular, the results are successfully compared to the linear stability theory. Furthermore, a zonal Reynolds averaged Navier-Stokes/large eddy simulation (RANS/LES) hybrid method has been employed for the same flow configuration to resolve more accurately the transitional flow than with the RANS approach. The analysis of the results highlights the strong impact of the LSB structure on the downstream boundary layer.