Effective inflow velocity reconstruction in separated airfoil flows using an effective control body model

Effective inflow velocity reconstruction recovers a reference velocity, representing the external inflow from a near-field velocity field affected by the airfoil. Under attached flow, the difference between local velocity and effective inflow is mainly associated with bound circulation. A circulation distribution on the airfoil profile can, therefore, provide a physically consistent induced velocity correction. Under separated flow, however, near-wall reverse flow and separated vortices distort the local velocity direction, making the airfoil surface inconsistent with the external effective flow. To address this limitation, an effective control body (ECB) model is proposed. It treats the airfoil and separated region as an integrated control body and relocates the circulation support boundary outside the separated region. Two variants define this boundary using a total pressure contour line or stagnation point streamlines. The method is evaluated using unsteady Reynolds-averaged Navier–Stokes flow fields around the Delft University 00-W2-350 airfoil. Under deep stall, the Shen2 model retains a pronounced directional deviation. Both ECB variants recover nearly parallel effective inflow streamlines, bring the inflow angle closer to the prescribed direction, and improve spatial uniformity. During unsteady separation, vortex evolution changes the induced velocity correction with phase, but both variants maintain small inflow angle deviations. Under the investigated two-dimensional separated flow conditions, relocating the circulation support boundary outside the separated region makes the induced velocity correction more consistent with the external flow. The ECB model, therefore, provides a physically motivated approach to effective inflow reconstruction for the examined cases.