Comparison of the results of RANS- and ILES-based calculations for a thick dropd-shaped profile at low Reynolds numbers

Numerical modeling of a flow around a symmetrical thick drop-shaped airfoil in a non-stationary formulation was carried out at Reynolds numbers $\operatorname{Re}=10^4\div 10^5$ and in the range of angles of attack $\alpha=-10\div10^\circ$. The calculations were performed in the approximation of the unsteady Reynolds-averaged Navier–Stokes equations (URANS) using the implicit large-eddy method (ILES). In the URANS approach, the position of the laminar-turbulent transition was determined based on the models $k{-}kl{-}\omega$, $k{-}\omega{-}\gamma{-}\operatorname{Re}_\theta$ (Menter model) and ($k{-}\omega $)-SST models with a given laminar flow region. It is shown that the position of the laminar-turbulent transition region has a significant impact on the flow structure and aerodynamic characteristics of the airfoil. Comparison of the results obtained using the ILES approach with experimental data showed that they are in good agreement. URANS calculations did not allow obtaining results consistent with experimental data. Fixing the laminar-turbulent transition point in the URANS calculation in some cases made it possible to correct the results.