Wall-pressure sources in the trailing edge turbulent boundary layer

The present study investigates the scale-dependent links between turbulent structures and wall-pressure fluctuations in the turbulent boundary layer close to the NACA0012 trailing edge. The three-dimensional velocity fields and wall-pressure signal are simultaneously measured at Reτ = 216 . The velocity and wall-pressure fluctuations are decomposed into intrinsic mode functions (IMFs) of increasing scales using empirical mode decomposition. The most correlated IMFs for wall-pressure and streamwise velocity fluctuations occur when they share similar length scales. The correlation patterns for the smaller scales indicate that hairpin vortices and hairpin packets are the dominant pressure sources. The conditional averaged velocity fluctuations based on the zero-crossing events and peaks of the wall-pressure IMFs are analysed, revealing the spatial–temporal signature of turbulent structures on wall-pressure fluctuations. High scale-dependence and convection nature are detected for responsible turbulent structures. For the high-energy wall-pressure IMFs, the pressure peaks are caused by the shear layer induced by the impinging and splitting of alternating positive and negative motions. Conversely, the zero-crossing events are related to a single large-scale motion.