VELOCITY SPECTRA AND SCALE DECOMPOSITION OF ADVERSE PRESSURE GRADIENT TURBULENT BOUNDARY LAYERS

Adverse pressure gradient turbulent boundary layer velocity spectra at high Reynolds number (7100 ≤ Re ≤ 8600) are compared to a zero pressure gradient case from Zimmerman (2019); Zimmerman et al. (2019) at matching Reynolds number. Wall-distance scaling observed in the zero pressure gradient spectra is also observed in the adverse pressure gradient spectra. Effects of varying Re on the velocity variances and Reynolds shear stress are studied by comparing the present data with the data of Monty et al. (2011) at lower Re (≈ 1900) and varying Clauser pressure gradient parameter. Cases at similar and Reynolds number, but with varying flow history are also studied. Increases are observed in the outer peak of u²⁺, v²⁺, and -uv⁺. Under a scaling that uses a hybrid velocity u_hyb there is similarity between the outer region profiles of spectrally-decomposed variances and Reynolds shear stress.