Presenter: Rahul Deshpande

Townsend (1976) introduced the concept of active and inactive motions for high Reynolds number wall-bounded turbulence, where the active motions are solely responsible for producing the Reynolds shear stresses in the inertial region.  In this talk, we present a data-driven methodology to segregate the active and inactive components of the velocity fluctuations. The inactive motions are found to consist of contributions from classical (self-similar) attached eddies and very-large-scale (super-structure) motions. Amongst these, the pure attached eddy contributions are shown to produce a clear k⁻¹ scaling for the streamwise velocity component for both streamwise and spanwise wavenumbers (k). This is consistent with a logarithmic profile for the inner-scaled streamwise velocity variance across the inertial region, lending empirical support to the attached eddy model of Perry & Chong (1982).