This paper presents the computational studies done at ONERA in the context of the 4 th AIAA CFD Drag Prediction Workshop. Furthermore, it gives a detailed description of the far-field methods developed in the Applied Aerodynamics Department. Concerning the DPW4 configuration, a grid convergence study and a downwash study are proposed. Then, the effects due to Mach and Reynolds numbers variations are quantified. All the multiblock structured grids used in this work have been provided by Boeing to the DPW community. All the RANS computations are performed by using the ONERA-elsA solver with the Spalart-Allmaras turbulence model, the solutions are post-processed with the ONERA-ffd72 far-field drag extraction tool. Concerning drag predictions, a very good agreement has been observed between ONERA-elsA results and the near-field drag coefficients (pressure and friction) computed by other DPW4 participants such as Boeing or Airbus. Moreover, the far-field software ffd72 gives to ONERA the singular capability to determine the values of the different physical drag components (viscous, wave and lift-induced productions). Concerning the pitching moment, ONERA results are very close to Boeing, Airbus or DLR predictions. Nomenclature Ma = Mach number Re = Reynolds number α = angle of attack c = wing chord

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Transitional Shockwave/Boundary Layer Interactions (SBLI) is studied experimentally. Experiments are conducted on a hollow-cylinder flare model in the R2Ch blowdown facility at a Mach number of 5 for three different Reynolds numbers in the transitional regime. Unsteady wall pressure measurements are conducted along with mean and unsteady heat flux measurements and high-speed Schlieren imaging. The images are then processed using Proper Orthogonal Decomposition (POD) and Spectral Proper Orthogonal Decomposition (SPOD) to extract relevant information. Two main phenomena are identified and documented: the oblique modes traveling in the shear layer above the recirculation region and the streaks appearing in the reattachment region. New results illustrating the multiple physical origins of the streaks, either linked with globally unstable modes and convectively unstable mechanisms, are discussed.