During the ascent phase of a launcher, base buffeting may occur for transonic conditions which may result in large
side loads on the nozzle. This effect is well known and has been subject of extensive studies in literature. The present work is conducted in the framework of the ESA TRP “Launcher Base Flows and Shock Interactions Regions Improved Load Characterisation”, where high speed PIV measurements and unsteady pressure measurements performed in the DNW-HST on a 1:60 scale Ariane 5 are compared to detached eddy simulations for the same configuration and flow conditions. The main goal of the investigation is to identify how well the computations are capable of predicting the salient features of the transonic buffeting phenomenon.