Study of Stall Development Around an Airfoil by Means of High Fidelity Large Eddy Simulation

Large Eddy Simulation of the bubble bursting process over a NACA-0012 airfoil at indicates that the flow at a fixed angle of attack below the critical stall value exhibits a short (with respect to Gaster's criteria, Gaster, Number CP-4 in AGARD, 1966) Laminar Separation Bubble (LSB) at the leading edge of the airfoil. The airfoil is smoothly pitched-up through the static stall angle to reproduce the bursting process of the short LSB that initiates a leading edge stall typical of low Reynolds number airfoil. The temporal evolution of characteristic length scales is monitored during the transient flow. Particular attention is paid to the characteristic time involved during the growth and bursting of the LSB. A recent empirical bursting criterion is used to analyse the LES results.