A hybrid DNS/wall-modeled LES approach for quantitative prediction of airfoil stall

A hybrid simulation approach combining direct numerical simulation (DNS) and wall-modeled large-eddy simulation (WMLES) is proposed to predict airfoil aerodynamics near the stall point. The DNS is solved only in the region near the leading edge to reproduce the development of the laminar boundary layer and subsequent laminar-turbulent transition. Furthermore, an external force term is introduced into the WMLES part, so that the velocity and turbulent kinetic energy profiles match those obtained from the DNS part. For validation, the flows around the Aerospatial A-Airfoil at a near-stall condition are simulated at two different Reynolds numbers R e c = 2.1 × 1 0 6 and 1.0 × 1 0 7 . The results show that the hybrid simulation methodology reproduces the transition and downstream boundary-layer development more accurately than the conventional WMLES. Consequently, the difference in the aerodynamics at the two Reynolds numbers is quantitatively well predicted. The computational cost at the high-Reynolds-number condition ( R e c = 1.0 × 1 0 7 ) is less than 1/100 of that of the wall-resolved LES, realizing quantitative prediction of near-stall aerodynamics with affordable computational cost.