Abstract The role of streamwise length scales (λx) in turbulent skin friction generation is investigated using a direct numerical simulation data set of an incompressible zero pressure gradient turbulent boundary layer and the spectral analysis based on the Fukagata-Iwamoto-Kasagi (FIK) identity by Fukagata et al. [K. Fukagata et al., Phys. Fluids 14, L73 (2002)]. The total skin friction generation associated with motions scaled with local boundary layer thickness δ of λx<3δ and λx>3δ is assessed.
