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Reynolds-number effects in the adverse-pressure-gradient (APG) turbulentboundary layer (TBL) developing on the suction side of a NACA4412 wing sectionare assessed in the present work. To this end, we analyze four cases atReynolds numbers based on freestream velocity and chord length ranging from Rec= 100, 000 to 1,000,000, all of them with 5 degree angle of attack. The resultsof four well-resolved large-eddy simulations (LESs) are used to characterizethe effect of Reynolds number on APG TBLs subjected to approximately the samepressure-gradient distribution (defined by the Clauser pressure-gradientparameter beta). Comparisons of the wing profiles with zero-pressure-gradient(ZPG) data at matched friction Reynolds numbers reveal that, for approximatelythe same beta distribution, the lower-Reynolds-number boundary layers are moresensitive to pressure-gradient effects. This is reflected in the values of theinner-scaled edge velocity Ue+ , the shape factor H, the components of theReynolds-stress tensor in the outer region and the outer-region production ofturbulent kinetic energy. This conclusion is supported by the largerwall-normal velocities and outer-scaled fluctuations observed in the lower-Reccases.Thus, our results suggest that two complementing mechanisms contribute tothe development of the outer region in TBLs and the formation of large-scaleenergetic structures: one mechanism associated with the increase in Reynoldsnumber, and another one connected to the APG. Future extensions of the presentwork will be aimed at studying the differences in the outer-region energizingmechanisms due to APGs and increasing Reynolds number.

Turbulent boundary layers around wing sections up to Rec = 1,000,000