Energy transfer in the inner and outer layers of APG TBLs

The spectral distribution of energy, production and pressure-strain in channel flows, zero-pressure-gradient (ZPG) turbulent boundary layers (TBLs) and non-equilibrium adverse-pressure-gradient (APG) TBLs are investigated to understand the energy transfer in the inner and outer layer of APG TBLs with small and large velocity defect cases. In the inner layer, the inner-scaled spectra demonstrate that the relative size and wall-normal position of structures with respect to each other remain similar as the velocity defect increases from channel flow to APG TBL with a large velocity defect. Furthermore, the 2D spectral distributions show that the relative size of energy-carrying and energy-transferring structures does not profoundly change with velocity defect in the outer layer. These similarities, along with others that will be presented at the meeting, suggest that the energy transfer mechanisms in the inner and outer layers may not be significantly affected by the velocity defect and remain almost the same within one layer in channel flows, ZPG TBLs and APG TBLs.