Pseudo-Unsteady Two-Dimensional Viscous–Inviscid Interaction Method for Steady Transonic Flows

Driven by increasingly stringent efficiency requirements, aerodynamic optimization is nowadays integrated early in the design process of new aircraft. Quick evaluation of the performance of one design configuration can be obtained by using methods based on viscous–inviscid interaction. These approaches usually come at a lower computational cost than Reynolds-averaged Navier–Stokes (RANS) computations and predict more accurate values for the aerodynamic loads and improve shock modeling in transonic conditions compared to purely inviscid techniques. This study presents a novel two-dimensional pseudo-time-dependent formulation of the viscous compressible boundary-layer equations in the context of the quasi-simultaneous coupling strategy for steady viscous–inviscid calculations of compressible transonic flows in external aerodynamics. The proposed methodology is first evaluated on subsonic attached and mildly separated flows around a symmetrical airfoil at a high angle of attack. Predictions in transonic configurations are then shown on symmetrical and supercritical airfoils and are compared to RANS solutions and experimental measurements. Good agreement with reference results is observed for flows with limited separation regions and for transonic flows.