Embraer Contribution to DPW-8/AePW-4: Scatter WG Two-Dimensional Cases

This paper outlines the contributions of Embraer to the 8th Drag Prediction Workshop/4th Aeroelastic Prediction Workshop in the Scatter Working Group. Test cases 1a/1c (ONERA OAT15A airfoil) and 1b (Joukowski 12% symmetric airfoil) were executed using CFD++. Obtained results for Case 1a showed that, especially in the transonic buffet region, meshes with higher non-orthogonality errors tend to maximize the dispersion of aerodynamic coefficients between turbulence models. Furthermore, the occurrence of an early residual convergence limit was more frequent with such meshes when subject to significant shock-induced separation. With sufficient attention to mesh refinement and quality, dispersions of about 4.0 drag counts nevertheless remained near transonic stall. Case 1b highlighted that suitable coefficients and residual convergence is obtained when careful attention is given to mesh quality and to a comprehensive problem definition. The Joukowski airfoil subsonic drag scatter between the two finest studied grid levels lies within 0.1 drag count for a symmetric freestream condition. Case 1c illustrated that even in a more challenging transonic case, constrained problem definition and setup enabled much lower scatter than previously reported in Case 1a. Drag scatter considering the finest levels of each grid family is reduced to 0.2 drag count for the selected AOA = 1.50°. Pressure and skin friction chordwise distributions confirm the mesh convergence trend.