  The inner-outer interaction model (Marusic, Mathis & Hutchins, Science, vol.
329, 2010, 193-196) and the attached-eddy model (Townsend, Cambridge University
Press, 1976) are two fundamental models describing the multi-scale turbulence
interactions and the organization of energy-containing motions in the
logarithmic region of high-Reynolds number wall-bounded turbulence,
respectively. In this paper, by coupling the additive description with the
attached-eddy model, the generation process of streamwise wall-shear
fluctuations, resulting from wall-attached eddies, is portrayed. Then, by
resorting to the inner-outer interaction model, the streamwise wall-shear
stress fluctuations generated by attached eddies in a turbulent channel flow
are isolated. Direct comparison between the statistics from these two models
demonstrates that they are consistent to and complement each other. Meanwhile,
we further show that the superpositions of attached eddies follow an additive
process strictly by verifying the validity of the strong and extended self
similarity. Moreover, we propose a Gaussian model to characterize the
instantaneous distribution of streamwise wall-shear stress, resulting from the
attached-eddy superpositions. These findings are important for developing an
advanced reduced-order wall model.
